Test to detect breast cancer death low risk

TT, New Delhi, July 2: A molecular test that pinpoints patients with a very low risk of death from breast cancer even 20 years after diagnosis and tumour removal may help such "ultralow" risk patients avoid aggressive overtreatment with chemotherapy.

The test, based on a 70-gene signature and approved by the US Food and Drug Administration a decade ago, can identify early-stage breast cancer patients who have a very low risk of recurrence, doctors said on Thursday after conducting a clinical study.

The study - by US and Swedish researchers - has suggested that the 70-gene test may be used by doctors and patients to make decisions on whether to opt for endocrine chemotherapy, sometimes prescribed to avoid recurrence of tumours after surgery.

"This is an exciting advance because 20 to 25 per cent of tumours diagnosed may be ultralow risk," said Laura Esserman, a breast cancer specialist at the University of California, San Francisco, and lead author of the study published on Thursday in the Journal of the American Medical Association Oncology.

"Women who have a tumour classified as ultralow risk can be reassured that their long-term outcome is expected to be excellent with or without endocrine therapy."

The 70-gene test is available in India through private companies.

Although oncologists have earlier discussed the existence of ultralow risk tumours, Esserman said, the new results provide the first evidence to show that the test could be used at the time of diagnosis to identify ultralow risk tumours.

Cancer researchers have for over a decade been trying to find ways to classify breast tumours according to their molecular or genetic signatures. These efforts are relevant to cancer treatment because multiple studies have established that breast tumours can display diverse behaviour - some tumours are aggressive and grow fast, while others pose extremely low risk and may not pose a risk to the life of a woman in her normal lifetime.

A US study had only earlier this month questioned the value of routine mammography-based screening, iterating messages from earlier studies from Canada, Norway and the US that the detection of extremely slow-growing tumours may lead to the overtreatment.

In the new study, Esserman and her colleagues assessed breast cancer patients over 20 years to identify cancers with no risk or almost no risk of metastasis - the life-threatening spread of the tumour from the primary site to other parts of the body.

The 70-gene test classified 98 women (15 per cent) among a group of 652 women with breast cancer as "ultralow risk", indicating that such tumours were an inherent part of the range of breast cancers.

The women with the ultra-low risk tumours had an excellent prognosis, whether or not they had used the endocrine therapy for two years, the researchers said.

"Such tools will enable doctors to better personalise therapy to safely minimise treatment and reassure women if a cancer is ultralow risk," Esserman said.