Ovarian transposition

Does the use of ovarian transposition, prior to radiation therapy in women with cancer, reduce the risk of primary ovarian insufficiency? Does it reduce the risk of loss of ovarian reserve?

The quality of the evidence supporting ovarian transposition for fertility preservation varies. Most studies of the use of ovarian transposition (OT) for fertility preservation in women with cancer examine ovarian function after treatment for cervical cancer, although OT is relevant to Hodgkins lymphoma and some brain and spinal tumors. There are no randomised controlled trials and very few studies that compare patients who undergo ovarian transposition with patients who don’t. Many studies also use surrogate end-points for ovarian function (FSH levels, vasomotor symptoms and estrogen levels) and we were unable to find any studies that looked at birth rates in this population.

Only one study looked at ovarian function in women with cancer (mostly cervical) after OT compared to cancer patients without OT. They found that ovarian function was significantly better in women who had undergone OT prior to radiation therapy (5 years ovarian function 60.3% after OT versus 0.0% without OT p < 0.001)^.[1] This study is weakened by its retrospective design, small number of women included and the heterogeneous nature of treatments women received.

Other studies looking at ovarian function in women with cervical cancer after OT and pelvic radiation also found that a proportion of these women retained ovarian function. This proportion varies from 41%^[2] and 64%^[3] to 83%.^[4] None of these studies included a control group. However, a systematic review and meta-analysis of 24 studies of ovarian transposition in women with cancer (majority cervical), found that overall OT is associated with preservation of ovarian function. They also noted the need for more research including non-OT control groups.^[5]

Radiotherapy

Radiation to the pelvis contributes to loss of ovarian function, even when OT is performed. Du et al examined women with cervical cancer who had undergone OT and compared three different radiotherapy protocols. They found that limiting radiation dose in some protocols may improve the chance of preserving fertility.^[6] Again, this study was limited by the number of women and length of follow-up. A similar study found that 60% of women treated by external radiation therapy experienced ovarian failure, compared to 90% receiving brachytherapy.^[4]

The site of ovarian transposition above the iliac crest may determine if the radiotherapy field includes the ovaries. One study found that ovaries transposed to a site more than 1.5 cm from the iliac crest were more likely to retain their function.^[7] However, this is contradicted by another study that found transposition of ovaries more than 2 cm above the iliac crest did not completely protect ovaries from the radiation field.^[6] Recommendations on radiotherapy and surgical protocols for ovarian transposition are beyond the scope of this guideline.

Risks

Risks from ovarian transposition include ovarian torsion, ovarian cysts and seeding in the transposed ovaries. A systematic review by Gubbala et al found that these risks were low.^[5]