A couple of studies were presented Wednesday that evaluated the provision of less treatment in an effort to reduce the harms of treatment. I took note of what Dr. Hyman Muss, (from the University of North Carolina at Chapel Hill) said on Wednesday evening: “the best therapy is not always the most therapy”.
The first study looked at older women with low risk tumors. This was from the Prime 2 trial and presented by Dr. Ian Kunkler, professor of clinical oncology at the Edinburgh Cancer Research Center. The harms of radiation are well documented and this study evaluated whether older patients with more benign tumors might omit radiation and be spared the morbidity associated with radiation treatment. Data from women who were randomized to whole breast radiation or no breast radiation after lumpectomy showed that older women with low risk breast cancer (small hormone positive tumors) who did not receive radiation with a lumpectomy were no more likely to die of breast cancer than women who did receive radiation. Only 1% experienced metastasis and the majority of deaths were not from breast cancer.
While there is no difference in overall survival, radiation does reduce local recurrence of hormone positive breast cancer by 2.8% over 5 years: to just 1.3% compared to 4.1% recurrence for non-radiation. Getting the radiation upfront lowered the chance of the tumor growing back to 1% from 4% but there was no effect on survival.
Furthermore, for the relatively few women with tumors that do grow back, because they have not previously had radiation, they would remain eligible for a second lumpectomy this time followed by radiation. In summary, this gives women (who fit the above criteria) a choice about having radiation that does not appear to compromise their survival.
Another area discussed regarding reduced treatment was about surgery for women with metastatic cancer. Because metastatic cancer has spread beyond the breast, this surgery is sometimes referred to as “local control”. Dr. Seema Khan provided a discussion of data after two studies (one from India and one from Turkey) evaluating the benefit of surgery for women with metastatic disease. There were some differences in the trial design between the two studies presented. Dr. Khan noted the difficulty of designing trials given heterogeneity of metastatic cancer and the range of systemic therapies used. Despite these variations, the key finding of both studies is that there was no difference in overall survival for women with metastatic cancer who did or did not have surgery to remove the breast tumor.
In addition to these two studies presented at this year’s SABCS, there are four additional studies evaluating this same issue that are taking place around the world. When those studies are complete we’ll need to reassess the current assumptions in light of any new data. But based on the studies presented today, surgery should not be offered to asymptomatic women with metastatic breast cancer.