According to research published by the British Medical Journal, one in three breast cancers that are detected by mammogram are actually harmless. Sometimes cancer cells can be present without spreading or they may automatically resolve with the help of the person’s own immune system. Scientists now suggest that many invasive treatments for cancer are unnecessary.
Incidence of breast cancer was studied in the United Kingdom; Manitoba, Canada; New South Wales, Australia; Sweden and parts of Norway.
It was found that the incidence rose with the introduction of routine mammogram screening and over-diagnosis of breast cancer tumors were estimated to occur in 52 percent of cases. Detection of otherwise benign tumors is thought to be the cause of this increase. Researchers did not mention whether the radiation used in the mammogram-screening technique might contribute as well. They also found that when women exceeded the age limit for a mammogram that the incidence of breast cancer dropped slightly.
The authors of the study said:
“Screening for cancer may lead to earlier detection of lethal cancers but also detects harmless ones that will not cause death or symptoms. It is well known that many cases of carcinoma in situ in the breast do not develop into potentially lethal invasive disease. In contrast, many find it difficult to accept that screening for breast cancer also leads to overdiagnosis of invasive cancer. Harmless invasive cancer is common.”
This puts women at risk of undergoing radiotherapy with its serious side-effects and of potentially losing their breasts without cause.
The charity, Breakthrough Breast Cancer, disagrees with the research, saying that women should still have mammograms. Dr. Sarah Cant said, “Based on all the current evidence, we believe the benefits of detecting breast cancer early still outweigh the risks.”
Source: BMJ 2009;339:b2587
Joanna is a freelance health writer for The Mother magazine and Suite 101 with a column on infertility, http://infertility.suite101.com/.