Why there is no screening program for ovarian cancer in Australia
In Australia, more than 1,500 women are diagnosed with ovarian cancer every year. Sadly, most women are diagnosed with this disease at advanced stages 3 or 4, resulting in a lower survival rate.
There is currently no population-based screening program for ovarian cancer in Australia. A screening program provides a diagnostic test to catch the cancer early for people who show no signs of the disease. If an ovarian cancer screening program were to be available, we could shift the cancers diagnosed from late to early stages when treatment is more effective and survival would be better.
Here I detail what is delaying an ovarian cancer screening program in Australia.
1. There is a lack of reliable screening tests
We can use blood tests (CA125) or ultrasound to detect ovarian cancer, but unfortunately these are not very reliable. CA125 is a tumour marker expressed by most ovarian cancer patients at advanced stages (stages 3 and 4), however up to 50% of patients with stage 1 ovarian cancer will not have elevated blood concentrations of CA125. This means that some patients will have false negative results which will miss the cancer. High levels of CA125 can also be caused by common conditions such as endometriosis or adenomyosis or even arthritis. This means that some patients will have false positive results which may indicate cancer is present, when it is actually not.
Ultrasound is also unreliable because it will show large ovarian masses (late stage) but may miss small cancers (early stage).
If the CA125 or ultrasound tests indicate there is further investigation required, explorative surgery may be recommended. This may result in unnecessary surgery if the initial test results were incorrect. All surgeries carry risk, and this could also result in unwanted surgical outcomes should complications occur.
Therefore, these tests alone are not useful as a screening test for ovarian cancer in people with no symptoms. They should only be used in people where ovarian cancer is suspected, or during treatment to monitor response. Research continues to search for tumour markers and imaging tests that are more accurate and reliable.
2. It's not very common
Population-based screening is only introduced when a range of conditions are met. One of these conditions is that a cancer should be common with a high morbidity and mortality rate. While the mortality rate for ovarian cancer is high, the lifetime risk of developing ovarian cancer is about 1.3%, so it doesn’t affect a large proportion of the Australian population.
3. We don’t know what causes ovarian cancer
We don’t know what causes ovarian cancer or fully understand how it develops. Some evidence suggests that the origin of some types of ovarian cancer is in the Fallopian tube rather than in the ovary. We need to understand and identify the early stages for a screening test to be implemented.
4. There are only vague early symptoms
Ovarian cancer patients develop symptoms (urinary frequency, fullness, increase in abdominal size or changes in bowel habits) that may be confused with other benign conditions such as irritable bowel syndrome, an upset stomach or bladder infections. Unfortunately, these symptoms normally reflect late stage disease. There are no specific symptoms that are associated with early stages of ovarian cancer.
5. Lack of research evidence
There is evidence that screening will not reduce the number of deaths.
Randomised controlled trials would be required to compare survival rates in people who are assigned to ovarian cancer screening, and those who are not (controls) and follow them over time. For example, randomised controlled trials for breast and colorectal cancer (which have current screening programs) have consistently shown reductions in disease specific mortality in the region of 20%.
6. Lack of research funding
There is a lack of government funding which also delays the search for a reliable screening test. In the past, medical problems that received sufficient medical research funding were solved. For example, survival of leukaemia, lymphoma or breast cancer were very poor when I was a young medical student some 40 years ago. Now those outcomes are excellent, which is the result of hard work that required funding. That is why organisations, such as the Cherish Women’s Cancer Foundation exist – to develop kinder, gentler and more effective treatments for women affected by gynaecological cancer.
In conclusion until we can find a reliable screening test and better understand the causes of ovarian cancer a population-based screening program for ovarian cancer is not currently viable.
For more information on diagnosing ovarian cancer, visit the Ovarian Cancer page.
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