‘Surprising gaps’ in ovarian cancer research, says report
Ovarian cancer, often called the “silent killer”, is poorly understood by researchers and often does not even arise in the ovaries, a US panel said.
With no cure in sight, no reliable early screening tests and a lack of effective treatments for the cancer, the National Academies of Sciences, Engineering and Medicine called for a series of steps to close what it said were “surprising gaps in the fundamental knowledge about and understanding of ovarian cancer”.
“The committee concludes that a substantial proportion of carcinomas labeled ‘ovarian’ may actually originate outside the ovary or arise from cells that are not considered intrinsic to the ovary,” said the 377-page, congressionally mandated report.
Many of these cancers “arise in other tissues besides the ovary, such as the fallopian tubes, which eventually metastasise to the ovary”.
Ovarian cancers kill about 14,000 women each year in the United States, where some 21,000 women are diagnosed annually with what is the nation’s fifth most common cancer.
Early symptoms may include bloating, pain while urinating or abdominal discomfort but often, no early symptoms are detectable.
About two in three women who are diagnosed with the cancer learn of it only once it is already advanced and has spread beyond its initial site.
Fewer than 30% of women who receive these late diagnoses will survive beyond five years.
Overall, fewer than half (46%) of all women diagnosed with ovarian cancer live for five years.
But there are research opportunities “that, if addressed, could have the greatest impact on reducing the number of women who are diagnosed with or die from ovarian cancers”, said the report.
These include placing a priority on research into high-grade serous carcinoma (HGSC), the most common and lethal subtype of ovarian cancer.
A better understanding of the range of other subtypes is also needed, the report said.
Women with mutations in their BRCA1 or BRCA2 genes are known to face a higher risk for ovarian cancer – along with breast cancer.
“Despite this important discovery of a major ovarian cancer risk factor, genetic testing and counselling for families at risk has not been universally adopted,” said the report, calling for more widespread genetic testing.
But since most women who get ovarian cancer have no family history of it, the report also called for a fresh effort to understand the risks of developing ovarian cancer, “including hormonal, behavioural, social and environmental factors”.
Another challenge involves the relative rarity of ovarian cancer.
Although it is the seventh most common cancer in women worldwide, clinical trials may enrol fewer participants than breast cancer trials, for instance, so researchers must get the most out of their data.
There is a “need to develop new clinical trial designs that are information-rich in terms of molecular characterisation and metadata so that clinically useful conclusions can be drawn quickly from smaller study enrolments”, said Jerome Strauss, chair of the committee that carried out the study.
Treatment is also a major obstacle. Most women with ovarian cancer are initially treated with platinum-based chemotherapy.
While many respond well at first, “virtually all recurrent ovarian cancers ultimately become resistant to current drug therapies”, said the report.