Bidirectional risk between ovarian and bowel cancers

A major review of international data suggests women with ovarian or bowel cancer face a significantly higher risk of developing the other cancer as well.

Although these cancers typically are studied separately, emerging evidence is pointing to a possible link between them, raising questions about whether shared genetic factors may predispose individuals to both malignancies.

Researchers analysed data from more than 20 large population studies spanning several decades which tracked hundreds of thousands of women diagnosed with ovarian, colon or rectal cancers.

The findings, published in the Korean Journal of Clinical Oncology and highlighted by The American Journal of Managed Care, found that women with ovarian cancer were around 70 per cent more likely to go on to develop colon or rectal cancer than women in the general population.

Meanwhile, women who had originally been diagnosed with bowel cancer, especially if that was in the colon, faced a nearly 50 per cent higher chance of developing ovarian cancer.

The researchers noted that these findings support a potential bidirectional relationship between ovarian and bowel cancers.

They also found that treatment modalities impact the development of secondary malignancies.

Chemotherapy appeared to significantly increase the risk of both colon and rectal cancers, suggesting a potential link between the treatment for ovarian cancer and subsequent bowel cancers.

Similarly, combined radiotherapy and chemotherapy was found to significantly increase the risk of rectal cancer.

“These findings emphasise the importance of monitoring women with ovarian cancer who undergo chemotherapy or combined treatments for the potential development of subsequent bowel cancers,” the study’s authors wrote.

Age and timing were also factors, with the increased risk of ovarian cancer following bowel cancer diagnosis being strongest in younger women and during the first few years after treatment.

The study also noted that other risk factors – such as diet, smoking, or family history – still play a part, and that the role of shared genetic risk factors also needs to be studied further.

“Future advanced genetic studies are needed to better understand the underlying molecular mechanisms,” the authors wrote.

“Additionally, the results emphasise the importance of careful cancer surveillance and early detection strategies for women with a history of either ovarian cancer or bowel cancer.”