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Constructively dealing with concerns about cancer clusters


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kNOw cancer risks at work, Cockle Bay Sydney, May 2015



Professor Tim Driscoll, Professor of Epidemiology and Occupational Medicine, University of Sydney



Constructively dealing with concerns about cancer clusters


Presentation outline:

Claims around cancer clusters are often contentious and complex. Professor Tim Driscoll draws on his experience dealing with cancer cluster investigations and the media interest they attract to outline how concerns should be dealt with constructively and effectively.

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Terry Slevin: Tim is Professor of Epidemiology and Occupational Medicine at the University of Sydney. He has been the founding member of the Cancer Council Australia's Occupational Environmental Cancer Committee. I had to twist his arm to do this presentation.

Tim has done a lot of work in the cancer clusters area, and it is a very challenging field in which to work, but I?ve asked him to talk today about constructively dealing with concerns about cancer clusters.

Please welcome Tim.

Tim Driscoll: Thanks. So, first just to show you where I?m coming from, in terms of what I think a cancer cluster is. Look, there are various definitions available, but basically, it just means you have got more cases of something. We are talking about cancer, so more cases of cancer than you would expect given how many people you have got and the length of time you are following them over.

It is usually focused on one topic of cancer, but not always, and to me, it doesn't imply a cause. It doesn't imply that there is some particular thing that is causing it, but a lot of the times you will hear that implication, sometimes it is stated, but often, it is just an implication that a cluster is not just a high number of cases, but a high number of cases caused by ?x?, and I don't think that is a very useful way to do it. I think it should just be looked at why you?ve got more than you want.

Now, just to get ourselves on the right tone and to establish my bona fide and to give you a bit of background about how these sort of things come up, this is a news report from a cluster investigation that I was involved in. If you could start that for me, please. DEMO:

Male Speaker: A joint investigation into a possible cancer cluster at the Jilalan rail yard, south of Sarina, is in full swing, independent Professor Tim Driscoll vowing to leave no stone unturned. Tomorrow, he will inspect the premises with past and present Queensland Rail employees.

Sarah Coates (Journalist): Professor Tim Driscoll is the face of calm in a storm of confusion and worry. The independent professor has been commissioned to oversee Queensland Health?s investigation procedures after a potential cancer cluster was identified at Jilalan rail yard a month ago.

Tim Driscoll: They are going to be concentrating on looking at the cases of cancer, and I?m going to be concentrating on looking at the size and the exposures and the work activities now and in the past.

Sarah Coates: Professor Driscoll will tour the site tomorrow and address a reference group set up to deal with current employee concerns.

Tim Driscoll: In the past, it would have been a lot of exposure to asbestos. So, if you were somewhere where there is a rail yard or a truck yard or wherever, if there is a lot of asbestos, you might expect problems with lung cancer and mesothelioma.

Male Speaker: We already know that the brake blocks that are used on the wagons and locomotives contain asbestos. There are also issues that we have around the dust that are around these areas.

Sarah Coates: To date, nine current and former stuff of the QR Jilalan rail yard have been diagnose with a range of cancers. Some are still undergoing treatment. Union officials say Queensland Rail is acting quickly and responsibly in getting to the bottom of the issue but until every factor is taken into account, no conclusions can be made. Tim Driscoll: At the end of the day, they want an answer as to whether their workplace is safe or whether their workplace is not safe.

Sarah Coates: Sarah Coates, Seven News.

Tim Driscoll: Okay, a face of calm in a storm of confusion and worry. Just remember that.

So, I put that up for two reasons. One, so I could put that up, but secondly, this is the sort of way it happens, and when I went up for that particular investigation, I was met at the airport by three cameras, and somebody was asking is there a celebrity here? And I was looking around for the celebrity, but it happened to be me on the day.

So, it is sometimes very big news and I didn't put the rest of it, but there were not a lot of cases of cancer and it is over a long period of time. The people were more worried, and the organization was worried for a whole lot of other reasons that I won't go into today, but it wasn't something that could just be dismissed. So, keep that in the background.

A few concepts that we need to keep in mind to do with cancer. One, it is a common disease. So, probably one in two men or one in three women in Australia have a lifetime risk of getting cancer. Generally, it is more common with age. There is usually a long latency, so a period of time between when you are exposed and when you develop a cancer, that is contributed to by that exposure. It has usually got one or more risk factors. It doesn't mean that if you identify a risk factor, that that is the cause for that person, but usually there are one or more risk factors. It has a random component, which I?m going to come back to, but it causes issues that, you know, if two of us were exposed to the same carcinogen, one of us might get cancer and one of us might not. One might get it in 15 years. One might get it in 25 years. So, it is not ? you don't necessarily get the same result from the same circumstances.

In terms of well, why is it tricky? There are a lot of reasons, but here are some of them in my mind. Most cancers can be caused by more than one type of exposure. So, it is hard if you see one cancer, you don't know whether it is due to exposure X or exposure Y and probably mesothelioma is one of the few exceptions to that.

Even if you think you know what the exposure is, that exposure can occur in a number of different settings. So, it is hard to know whether a particular setting was responsible for the exposure.

It is particularly tricky because of the long latency, which makes it quite difficult to connect to a particular exposure, and virtually always, you can't tell with any individual. You can take out a piece of the tumor but you can't look at the tumor and know what caused it.

And just remember that random doesn't mean even, and that is one of the things that is hard to get across to people, that randomness is clumpiness and say you?ll expect some high rates in some areas and some high rates in low areas just through chance. So, I just want to do with that issue of chance just a little bit.

So, you might get a chance occurrences or a high number of cases than you might expect just because through chance, you have got a number of different risk factors co-locating at the same time and the same group of people, or you mightn't have that, but you might just get the chance occurrence because through chance, you are going to get some areas that are slightly higher and some areas that are slightly lower than what is the average.

Now, I know you all love to see this normal distribution. This is a very quick and easy thing that I put together, but if you assume that there is some sort of distribution with the dotted line in the middle being the mean exposure of cancer in our population, and there will be some groups of the population who have a slightly higher risk and just a slightly lower risk due to chance, and some who have a very high risk and some very low, and some who have an extremely low risk and we don't worry about that, some that have an extremely high risk just through chance.

It can also happen because of high risk factors. There can be some problem in the workplace or in the community, but it can also happen just through chance, and it is very difficult, one, to explain that to people, but also to work out in a particular situation. Is it due to chance or is it because there is some problem there or that has been there? And this is another way of looking at this ? another quick and dirty thing that I put together a while ago.

Let's say that these are cases that occur randomly in the community. They are not due to any particular exposure, but they are just cases of cancer that occur in the community and there are various workplaces in the community.

Let's say you are sitting in that workplace and you are looking around and you are saying ?Well gee, there are six or seven cases of cancer in here over the last couple of years?. That is odd because I know somebody over in this workplace, they are not thinking about cancer and they might be up here with only one case, and they are probably not thinking too much about it, and the difficulty is in that first one, people are convinced often that there is a problem, and maybe, there is, but very commonly, there isn't, but the question is well, you know, what do you do about that?

So, in terms of when concerns arise about cancers, I?m not saying when I think they should, but when they tend to come up, it is when there are cases of the same cancer type or sometimes a higher number of a whole lot of different ones, but particularly, the same cancer type, when there is lots of cases and lots can vary from a couple to 50 or 100 depending on the workplace and the view of the people.

When younger people are involved, when there are concerning exposures around, so if people can smell something bad or there has been a rumor that something was stored over there or they know that they are working with asbestos, let's say. I particularly tend to come up in my experience when initial concerns, people asking perfectly sensible legitimate questions and they feel that those questions aren't dealt with appropriately, and generally, that is not in my experience because whoever it has gone to?so, usually, it has gone to management. It is not that management don't care. It is generally they are not sure what to do and things just, sort of, slide and often, it will go under the carpet and then, it will come back up again at a later time. And also, it is not uncommon that it comes up when there are some other issues, industrial relations issues if it is in the workplace or community issues if it is out of the workplace, and again, that doesn't mean it is made up. It just means that it is focusing people's mind, and I think well, what about blah that happened three years ago? People got cancer and you didn't deal with it and what is happening? Somebody else got cancer last week. This is clearly a problem.

Just to give you something to think about. This is a quote from Ken Rothman. Now, he is one of the gurus of Epidemiology. I wish I was Ken Rothman?and here is something he said in 1990.

So, to summarise ? ?I would recommend that we spend less time reacting to reports of disease clustering, less time trying to detect general patterns of disease clustering and less time developing new methods to conduct these activities.?

And he said this at the beginning of a meeting that was brought together to talk about cancer cluster investigations. So, it just, sort of, pulled the carpet from under everybody.

So, this is one of the gurus who said this 25 years ago, and this was a quote from a paper released a couple of years ago, which looked at a whole lot of cancer cluster investigations that had occurred since then, and here it is - ?It is fair to state that extensive efforts to find causes of community cancer clusters have not been successful. There are fundamental shortcomings to our current methods of investigating community cancer clusters.? and they are basically saying, ?well, it has been a waste of time? is almost what they are saying. So, just keep that in mind.

So, with that, you know, why bother? Why would we bother doing it? So, I?m one small epidemiologist, small in a number of ways, but a small epidemiologist and I?ve spent my career trying to avoid investigation of cancer clusters. And what I?m going to show you now are the ones that I have been involved in, so Mackay, Brisbane, Sydney, Canberra, Adelaide, Port Lincoln, Perth, and Dampier. So, that is in the last eight or nine years that I have been involved in, and I have tried to avoid virtually every one of those.

So, in Terry's words and he said this to me several times. ?It is not going to go away?. It isn't go to go away, and I should make a disclaimer now given what I?m going to say in a little while is that I?ve been paid for most of those, and I?m going to be advocating that we should, in general, we can't ignore it, but I?m just saying I?m not doing that because I want to get paid for it. I?m trying to avoid these, so just thought I should be upfront about it.

These are the cancer types of the ones that I have been involved in. So, it is just one sample and I put a whole lot out from the websites in Australia looking at other ones in Australia, say of brain cancer, which I haven't been involved in and leukemia, but these are the ones I have been involved in.

These are the settings that I have been involved in. So, several different types of cancer, lots of different types of settings. It is not just one particular workplace, not just heavy industry, for example.

So, I showed you this slide when the concerns arise. Now, this is when I think concerns should be raised, and there is a number of different things that you might look at in terms of making a decision with the bottom one perhaps you should never do anything.

So, my feeling is about well, in terms of a number of cases, you need just more than just a couple. Very, very occasionally, you might get interested if there are only a few cases, but it is very hard to make sense if you have only got two or three or four cases.

In terms of the type of cancer, I?d be much more concerned if it is a rare or very unusual type of cancer and if it is the same type, I?m more concerned than if it is a whole range of different types of cancers.

If it is young people, it is raising my suspicion more because that is not common because cancer is more common as people get older, and if I know that there are carcinogens there or they are heavily suspected and even more if there has been a carcinogen there that has been connected to the cancers that have been identified, that should be raising suspicions. It doesn't mean that there is a connection, but makes me more concerned about it.

So, in terms of the challenges of trying to investigate these, what should you do? Often, there is a lack of information, particularly about exposure and we are interested in the exposures in the past primarily, not current exposures, and there is very commonly not much information.

It is difficult sometimes to come up with a proper case definition, to know the population at risk, and to be able to identify all the cases that you want to identify.

The statistical tests are very difficult to interpret. I?m not going to go into detail of that for time, but basically, the standards tests that we usually can't use, we still use because there is nothing else to do, and so, it is very hard to know how to properly explain the results to people.

There is often a public perception that there must be a problem, almost regardless of what is found, and the context in which it occurs if it is an industrial relations context or a community outrage context, it is difficult to approach it in a logical manner. Sometimes, there are other agendas, people using it to get back at companies or unions or individuals, and often, if it is a big study, problems with ethics, restrictions, and requirements. I?m not saying that we shouldn't have the requirements, but they can certainly make it difficult, and the first big study I was involved in, it took me a year to navigate through the ethics requirements for it.

So, in terms of what I think you should do, firstly, I think you should get on to it quickly, and I haven't always done this for various reasons, but it is important to get on to it as quickly as possible.

I think being upfront and explain the challenges, go through some of the things that I have just mentioned here, make people understand it is not a straightforward process.

I think there should be an emphasis on looking at exposures and not on rates. I hate calculating the rates. I don't think it helps. Not that it doesn't help at all, but people get focused on it, and I think you should focus on the exposures for reasons I?ll tell you in a little while and look at the case characteristics. Look to see whether the people affected, did they work in the same place? Were they all clustered doing the same task in this little part of the building where there is this horrible smell because something was leaking from the ceiling or were they are scattered around doing completely different jobs at different times?

Very important to involve anybody who thinks that they have got an interest in it, whether you think they should or not. I think you should involve them all and have a reference group, not a steering group, not somebody telling me or you what to do, but have a reference group, so there is a good line of communication and give them regular feedback.

How much you do is very variable and just depends on the particular circumstances. So, I have had somewhere I have just gone and sat down with people and had a brief look around. I have been happy. They have been happy and that has been it. And I?ve have had others where it has been a very, very detailed investigation, and I think it depends on the circumstances and what the people want. I think you should always start by sitting down with the people who are worried and find out why are they worried and try to find out everything they are concerned about.

I generally say this is a two-stage approach. This one that focuses on exposures, and generally, you are interested in the past exposures, but that is often typical to get that information. So, you should also be interested in the current exposures, and also, from the current exposure point of view, at least at the end of the process, you would be able to re-assure people that there isn't a problem. If there isn't and if there is a problem now, you get it fixed.

I think you should look at all carcinogens, not just the ones that are connected to the cancer that comes up. So, if there is a particular cancer that people are concerned about and you say well look, there has only been a carcinogen ?x? that we have known as linked to it.

They won't just be thinking about that. They will be just thinking about cancer in general, and so, I think you should be looking at all carcinogens that could reasonably be there.

Overlapping with this, there will be another part of it that is looking at the epidemiological side, but as I said, I think it should be an emphasis on the case characteristics rather than the rates, and you are usually doing this at the same time and you need to keep communicating.

So, just to get your money's worth, I?ve brought you Driscoll's four principles for investigating cancer clusters. There used to be three, but I made up another one yesterday. It just shows you how valid they are.

Okay, the first one and this is perhaps the most important. This is my new one or I?ve always had it and I?ve just not stated it.

Is the cancer cluster investigation as I describe as a socio-scientific phenomenon? It is not just science. You can go in and do the science beautifully and be worse off at the end of it, and if you are doing that, you are not doing people a favor. So, you?ve got to take into account the context and the communication and find out what are the people worried about, and address that as best as you can. You can't address everything. People will have some whacky questions or they will have questions that you just can't answer. Well, that is fine. Get that out and say to them look, I can't answer that question for this reason or this is the best we can do to look into that.

Secondly, if there aren't any concerning exposures, if you have had a good look and there is nothing there, but there is a high rate, it is very likely that there is no cause for concern in that workplace, but if you are still concerned, you can't do anything more by crunching the numbers more in that place. You have to find another workplace with similar exposures, but not suspecting that there is a problem, just you pick it out of the blue and go and have a look there, and then, you can use your normal statistical tests. You have a good look and if you find a high rate there as well, well, you would probably start to worry, but if you don't find a high rate there, then it is much more reason for re-assurance, and that is basically what happened with the ABC cancer cluster in Brisbane when they then looked at the other ABC offices. There might have been a problem in that building in particular, but probably not. People were worried about the type of work and that same type of work was done elsewhere and problems weren't found there.

My third principle and another reason why I am saying focus on the exposures, not on the rates, is that if the rate isn't high, but you find a problem exposure, well, you have got to fix it. You don't say well, we didn't find a rate here, so we are not going to worry about that thing with the high level. And so, if you don't find exposures and you had a good look, there is nothing to fix, and if you do find exposures, who cares about the rate issue to be fixing the exposures? Sometimes, the rate does give a good guidance. I guess, if the rate isn't high, then sometimes, you can tell people that and that provides re-assurance, but it is not my experience that this is going to take away all of their concerns. You are still going to have to have a good look at the exposures. And the fourth one is that when concerns about cancer clusters arise, just through experience, you look in the literature, you look anywhere you like, it is very, very unlikely that it has been related to a problem in that workplace or the community. It is not impossible, but it is very unlikely. That is not a reason not to do something. It is not a reason to dismiss it and if you do dismiss it, you are doing the concerned people a disservice.

So, in terms of the key aspects, I?ve said this several times, but just in case you didn't get it, focus on the exposures and the concerns of the people. Find out what they are concerned about and try and address it. Listen to them and address them to the extent that you can, accepting that you can't do everything. Communicate early and often, and a couple of quotes to support me here. This is the same

Ken Rothman in that same talk, ?instead we should focus more on exposure assessment and where indicated, clean up.? So, I would like to say he got that from me, but since I wasn't working in the area at that time, it is going to be hard to justify that, but here, I?ve commented in parallel. It is not just because Ken says it.

And here is somebody that most of you know, Bernard Stewart. In his article about the ABC cancer cluster, he said at the end, what he was doing is supporting the fact that we shouldn't just look at the carcinogens of particular interest, we should look more broadly, and he said that ?a duty of care was seen to be met when the investigation was extended beyond the carcinogens that would account for the cluster to all carcinogens that were worrying those affected.? And like many things, I agree with Bernard on that.

In terms of advantages, well, one is, you can provide re-assurance that there aren't exposures there currently if you have a good look or if you find them, you can find them and you can fix them. So, you can certainly help the people who are currently working.

You can provide an insight into people as to whether their work previous exposures that might have been a problem and whether they are likely or not likely to have been responsible for the cancers they are concerned about.

And you can provide guidance to them as to whether the number of cases that they have got and the type of cases that they have got are unusual or not. You give a forum for their concerns to be addressed, and if you don't do it, they are still going to be there, and I think you just don't have any choice because the concerns aren't going to go away. So, I don't think it is something that you can ignore.

In terms of disadvantages and I?ve alluded to most of these I think. Lots of times you won't find a higher rate if you look, and if you don't find a higher rate, you can say well, why did we bother getting involved in this in the first place? People were worried about the high rate and there isn't a high rate, but it is usually not just about the rate. There are usually other concerns that they have, but often, you don't find a high rate.

It is very hard to find a causal connection even if there was one there, it is very hard to find out. These can be very costly, not for me of course. I come cheap, but all the resources that you have to put into it, it can be costly, both in terms of money, but also resources and effort, and often at the end of it, you don't have a definitive outcome.

Okay, so I?ve just come back to that first one where the news report was on. It was at Jilalan and I want to tell you what happened. So, if you could play this one for me, please.


Female Speaker: A suspected cancer cluster of the Jilalan rail yard has been investigated by a leading expert. Dr. Driscoll's report comes after initial fears last September were brought to light.

Female Speaker: A heavy weight finally lifted off the shoulders of rail workers from Jilalan's rail yard as results of an investigation into a workplace cancer cluster were today released.

Tim Driscoll: None of the reported cases appear to have been related to work-related exposures at Jilalan.

Female Speaker: The suspected cluster was originally uncovered in September 2009 with 15 reported cases over the past 20 years. Dr Driscoll began an investigation eight months ago testing the facility near Sarina for possible causing agents. The findings support that of Queensland Health own assessment. The report included recommendations that Queensland Rail has committed to taking on board and implementing it immediately.

Tim Driscoll: The ventilation in the lunchroom and the offices near there, which is not bad, but probably could be improved.

Female Speaker: Dr Driscoll's report also recommends that QR National inspect the building at the site for traces of asbestos.

Female Speaker: QR have begun meeting with victims, workers, and their families to discuss the outcomes of the final report.

Male Speaker: We are giving them the opportunity today to ask questions of the health professionals to help them understand the nature of the report.

Female Speaker: Dr Driscoll says the meeting with workers and victims went well, but they still have some concerns including diesel exposure.

Tim Driscoll: Before Jilalan was electrified, there was a lot more diesel than there is now and they are also interested in the possible contribution of personal risk factors like smoking.

Female Speaker: QR together with the Union will encourage employees to learn about cancer risk factors and make available screening and diagnostic tests for different types of cancers. Natalie Wynne, Win News.

Tim Driscoll: If you are interested ? if you don't believe me, you want to see what other people say. There are various documents in Australia. I agree with most of it, not completely. There is too much emphasis on rates for my liking in some of these, but basically, these documents are good.

I just wanted to end with this because I know Terry loves to put this in. A lot of the time people who are worried about cancer are worried about cancer in general, and you have to be careful how you bring it up, but it is helpful to just say to them look, there is a lot of things you can do to decrease your own risk of cancer, concrete things, and here are some of them.

So, in conclusion, cancer is a common disease. You expect clusters to occur just from chance. They usually are not going to be caused by exposure in the workplace and very, very unlikely that they are going to be due to an exposure that you didn't know about and you have just discovered a new thing. It is very, very unlikely, but you shouldn't dismiss them.

You have to communicate well. You should get on to it promptly. I think explain the challenges very upfront, emphasise on exposures, involve everybody you can, give regular feedback, change what you can change, and to finally finish, Terry would be disappointed if I didn't show him these photos.

And the one on the right, Terry, is the Swan River from the last weekend taken just for you.

Thank you very much.

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