CA125 test at GP could diagnose early stage ovarian cancer

The CA125* test could be useful at detecting ovarian cancer and various other cancers in the primary care setting, particularly for women aged >50 years, according to a study presented at the recent NCRI** Cancer Conference held in Glasgow, Scotland, UK.

The results were based on analysis of data of 50,780 women who, following symptoms of ovarian cancer, underwent CA125 testing at general practices in England between May 2011 and December 2014. Of these, 0.9 percent (n=456) were diagnosed with ovarian cancer.

Women aged >50 years had a threefold incidence of ovarian cancer compared with women aged <50 years (0.12 percent vs 0.4 percent).

Among women who had abnormal CA125 test results (>35 U/mL), 15.2 percent of those aged ≥50 years and 3.4 percent of those aged <50 years were diagnosed with ovarian cancer.

According to lead investigator Dr Garth Funston from the University of Cambridge, Cambridge, UK, the probability of ovarian cancer was 3 percent in women with a CA125 level of 51 U/mL, with 3 percent being “the level of risk at which NICE*** recommends urgent cancer referral.”

“Our work shows that CA125 is a very useful test for detecting ovarian cancer in general practice. This could help guide decisions made by GPs and their patients about the need for further investigation or referral,” said Funston.

“Diagnosing more cases of ovarian cancer at an early stage could have a big impact on survival and GPs are an essential part of that process,” added Dr Shibani Nicum from Oxford University Hospitals, Oxford, UK, and Chair of NCRI’s ovarian cancer subgroup, who was not involved in the research.

In a separate study using the same database, the CA125 test detected non-ovarian cancers in 3.7 percent of women (n=1,160) aged >50 years and 0.8 percent (n=161) aged <50 years.

Non-ovarian cancers were more commonly diagnosed in women with elevated CA125 levels than those with normal levels, regardless of whether the women were age >50 years (17.3 percent vs 2.8 percent) or <50 years (2.7 percent vs 0.7 percent).

The most common sites of cancer associated with elevated CA125 levels were the chest, abdomen, and pelvis, where levels were elevated in 49, 47, and 36 percent of women diagnosed with pancreatic, lung, and uterine cancer, respectively.

“Our findings … highlight that women with symptoms who are aged 50 years or more and have abnormally high CA125 levels frequently have other types of cancer. It is really important that GPs are aware of this to ensure these cancers are not missed,” said Funston.

“When managing symptomatic women with elevated CA125 levels, clinicians should take this into account and consider performing appropriate investigations for these cancers in order to avoid diagnostic delay, particularly if ovarian cancer has been excluded,” said Funston and co-authors.

“These findings could help doctors interpret test results and inform their decisions about which tests their patients need next. For instance, an older woman who has abnormal CA125 level should be considered high risk for ovarian cancer. Even if she does not turn out to have ovarian cancer, she might have another form of the disease and either way she will probably need an urgent referral,” added Nicum.

“These findings can also be used to expand on existing clinical guidelines, both in the UK and other countries, to improve ovarian cancer diagnosis at the national and international level,” she said.