A study suggests that some breast cancers may go away (regress) without treatment.
The researchers came to this conclusion after reviewing records of breast cancer diagnoses in Norway before and after the country started a national breast cancer screening program. The researchers compared how often breast cancer was diagnosed and treated over 6 years in two similar groups of women ages 50 to 64 with different breast cancer screening histories:
- One group had mammograms every 2 years during the 6 years they were followed, starting with the country's national screening program.
- The other group didn't have any mammograms during the 4 years before the national screening program started but did have one mammogram about 2 years after the national screening program started.
Because the two groups of women had similar characteristics that could affect breast cancer risk, the researchers thought the two groups would have similar breast cancer risk during the 6 years they were followed. But the researchers found that the women who had mammograms every 2 years were 22% more likely to have been diagnosed and treated for invasive breast cancer compared to the women who only had one mammogram during the study period. The researchers hypothesized that undetected breast cancers developed in the women who didn't get regular screenings, but went away without treatment.
It's hard to imagine how breast cancer could go away without treatment more than 20% of the time. Still, there are reasons why this could happen. In some cases, the genetic changes that caused the cancer cells to develop ultimately make it impossible for the cells to survive. In other cases, the immune system may be able to get rid of the cancer over time in some women.
This hypothesis is controversial and it's important to look at the results thoughtfully. The results DO NOT say that regular mammograms aren't valuable. Even if some of the undetected cancers may have gone away without treatment, most of the cancers didn't, and some were detected later, when they were potentially harder to treat.
These findings also DO NOT suggest that not treating breast cancer and hoping it will go away on its own is a good option.
Right now, annual screening mammograms starting at age 40 for all women are the best way for breast cancer to be diagnosed early, when it's most treatable. Depending on your unique circumstances, your doctor may recommend a more aggressive screening plan. Stick with the screening plan that you and your doctor have decided is the best for YOU.