Thousands of women with common type of early-stage breast cancer need not undergo chemotherapy, says a landmark US study.
The findings of the decade-long, largest-ever breast cancer treatment trial are going to change the way the disease is treated.
They also will bring immense relief to breast cancer patients as many of them, after surgery, can avoid the gruelling chemotherapy with its side-effects like hair loss, nausea, fatigue and, in rare cases, leukemia and heart attack.
The findings of the federally funded research conducted by a group named ECOG-ACRIN were presented at the annual meeting of the American Society of Clinical Oncology in Chicago on Sunday.
The Trial Assigning Individualised Options for Treatment (TAILORx), which began in 2006, covered more than 10,000 women diagnosed with early hormone-receptor-positive, HER2-negative, axillary-node-negative breast cancer. It followed their progress after surgery.
To find out if the cancer could grow or spread, a sample of the tumour was tested after surgery for 21 genetic markers.
Patients were divided into three categories on the basis of cancer recurrence scores of up to 10 out of 100, between 11 and 25 and 25 and above.
While the same study had previously found that those with recurrence scores up to 10 can skip chemotherapy, it was silent on cases in the grey area between 11 and 25 scores.
To find the answer, researchers divided the group with 11-25 scores into two. One group was given only endocrine therapy after surgery while the other was given both endocrine therapy and chemotherapy. Comparative study over a long period showed that treatment of chemotherapy to the second group did not make much difference.
The study found that women above 50 with a score of up to 25 do not need chemotherapy. Similarly, patients under 50 with a score of up to 15 also do not need chemo.
Chemotherapy may be avoided in about 70% of women when its use is guided by the test, said lead author Joseph Sparano, associate director for clinical research at the Albert Einstein Cancer Center in New York.
The results of the trial were published in the New England Journal of Medicine.