SINGAPORE - Screening for breast cancer in older women could do more harm than good, a study funded by the United States’ National Cancer Institute has found.
The study of over 54,000 older women who were screened for breast cancer found that among those aged between 70 and 74, there was overdiagnosis for 31 per cent of them. The figure was higher for those aged between 75 and 84 – at 54 per cent.
The study defined overdiagnosis as detecting a cancer that would not have caused symptoms in a person’s lifetime. Finding breast cancer could lead to worry and could even harm these women as they would be put through unnecessary treatment.
The results of the study by a team from the Yale Cancer Centre and Yale School of Medicine were published on Aug 8 in the Annals of Internal Medicine.
Oncologists here are somewhat divided on the issue. Singapore recommends mammograms every two years for women aged 50 and older.
Dr Sim Yirong, a senior breast surgeon at Singapore General Hospital and the National Cancer Centre Singapore, disagreed with the study’s findings, saying such thinking “implies that the treatment of breast cancer for this group of patients would have no added benefit”.
“It is well established through multiple randomised controlled trials that screening mammography is efficacious in reducing overall breast cancer mortality,” she said. “This is because treating breast cancer at an earlier stage is associated with an improved treatment outcome and overall survival.”
Dr Sim also pointed out that at the age of 70, women in Singapore can expect many more years of life than their counterparts in the US. The average life expectancy of a woman in Singapore is 85.2 years, compared with 79.3 years in America.
Women here who are 65 years old can expect to live, on average, till the age of 87.3 years.
About 16,000 women here are 90 and older.
Even the American Cancer Society and American College of Physicians said there are benefits to breast cancer screening if a person is expected to live for at least 10 more years, Dr Sim added.
She said local data from a study by the SingHealth Duke-NUS Breast Centre, where she is a senior consultant, has shown the benefits of detecting and treating breast cancer early in women aged 80 and older.
For those who are fit for surgery, the outcome is as good as that for those aged below 80. With surgery, their overall survival rate is better than that for women who do not have surgery.
Another reason for screening, Dr Sim said, is complications that could arise from untreated cancer.
“Without screening, elderly women tend to present with a later stage of cancer, and often require more intensive treatment. They are more likely to suffer more complications such as tumour bleeding and need regular wound care,” she said.
“They may also need frequent or longer hospital visits and admissions due to the complications of metastatic or advanced breast cancer. All these factors will impact their quality of life and adversely affect their caregivers and families.”
She fully supports continued mammogram screening for women aged 70 and older.
“The earlier breast cancer is detected, the better the prognosis and the more straightforward the treatment,” she said.
The Yale team said a limitation to their study was that it did not measure the difference in mortality rate between those who were screened and those who were not.
Associate Professor Mikael Hartman, who heads breast surgery at Singapore’s National University Hospital, said the risk of breast cancer increases with age. But he added that there is limited evidence on the benefits of screening in older women.
The benefits of screening for them include catching the cancer early, which increases the chances of successful treatment with minor surgery.
“Studies have shown older women who receive regular mammograms have a lower risk of dying from breast cancer compared with those who do not receive mammograms,” Prof Hartman said.
But he agrees that they also face potential risks such as getting false positives, which require further tests to ascertain if they have breast cancer. A false positive is a result that wrongly indicates the presence of cancer.
His advice is for women aged 70 and older to discuss with their doctors the benefits and risks before getting screened.
“Overall, while there is a benefit to older women continuing to receive regular mammograms, the decision should be made on an individual basis, taking into account the woman’s overall health, life expectancy and personal preferences,” he said.