According to a new study, not all breast cancer patients need to undergo chemotherapy. Researchers reached this conclusion through a large study that analyzed the specific genes in each women's tumor. It's a big step forward for personalized medicine and high-value care.
There are a few problems with the way breast cancer is dealt with, as well as with the type of treatment sought. Many patients (both men and women) follow the advice of celebrities, and not the scientific community. The answer is not always to jump to double mastectomy and hope the procedure removes all of the cancer. The answer is also not to start getting yearly mammograms in your 20's, and according to one new study the answer may not be chemotherapy, either.
Alright. Now that we see what shouldn't necessarily be done, here's perhaps a better approach.
This week the New England Journal of Medicine published strong evidence, saying that a genetic test may help determine which breast cancer patients should receive chemotherapy, and which should not. The study enrolled 10,253 women who had early stage breast cancer characterized by no metastasis, and positive for hormone receptor but HER2 negative.
Traditionally, chemotherapy would be recommended for these women followed by hormone therapy, mainly with tamoxifen. However, past data have suggested that chemotherapy might not be beneficial for all women who fit this profile.
One estimate suggests that chemo only improves five-year survival chances for just five percent of these patients. The goal of this study was to identify those five percent that can be helped with chemotherapy, and not expose the other 95 percent to the treatment as well as the medical bills and myriad of side effects that come with these drugs.
This is where high-value care meets personalized medicine. If a particular person's breast cancer has the mutation which the treatment targets, a benefit can be derived. Genetic testing can help us identify which patients have which mutations, and will therefore will benefit from the chemo.
To identify these specific patients, the researchers used Oncotype DX, developed by Genomic Health Inc., which has been around since 2004. The test looks at the activity of 21 commonly mutated genes and assigns a score based on how likely it is the cancer will metastasize. A low score indicates a more benign growth while a high one indicates a higher likelihood the tumor will spread. The former has been associated with tumors that don't need chemotherapy, while the latter indicates a tumor that should receive the treatment. This study tested that hypothesis on a much larger scale than had previously been done.
The researchers separated the women into three groups: low score (<10), intermediate score (11-25) and high score (26+). Low-score patients (15.9 percent of participants) received only standard hormone therapy (i.e. tamoxifen) but no chemo; intermediate patients (68 percent of patients) were randomly assigned either chemotherapy and hormone therapy, or just hormone therapy; and all members of the high risk group received both. At press time, only data from the low score group was released.
For the low score group, the five-year survival rate was 98 percent. Furthermore, less than one percent of those cancers reoccured in a tissue other than the breast, and just 1.3 percent of women had recurrence of the cancer anywhere. Taken together this provides strong evidence that women with low scores on the Oncotype DX do not necessarily need to undergo chemotherapy.
There is no roadmap for cancer treatment, because everyone's cancer is different, even if the tissue of origin is the same. However, as the personalized medicine revolution rolls on, studies like this will provide tremendous help to patients and their physicians.