Re: Long-term Outcomes of Invasive Ipsilateral Breast Tumor Recurrences After Lumpectomy in NSABP B-17 and B-24 Randomized Clinical Trials for DCIS

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Recently, Wapnir et al. ( 1 ) provided detailed results of the long-term outcomes in ductal carcinoma in situ (DCIS) patients from the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-17 and B-24 randomized trials. The data reported are very important because for every four diagnoses of invasive breast cancer, now there is one diagnosis of DCIS. However, understanding of the biology of DCIS and its interplay with the host microenvironment remains elusive ( 2 ).

As described by Wapnir et al. ( 1 ), adjuvant radiation therapy in the NSABP B-17 trial substantially reduced the incidence of ipsilateral breast tumor recurrence from 35.0% in the lumpectomy only (LO) group to 19.8% in the lumpectomy followed by radiotherapy (LRT) group [see table 2 in ( 1 )]. Recurrence is an important endpoint in a woman’s quality of life because it is associated with much stress and further breast procedures. However, this reduction in local recurrence was not reflected in any survival advantage from adjuvant radiotherapy. In fact, the irradiated group of patients suffered a slight increase in mortality after 15 years of follow-up compared with the patients assigned to the no radiation group; total mortality was increased to 17.1% in the irradiated group compared with 15.8% in the nonirradiated group, explained by breast cancer mortality increasing to 4.7% from 3.1% [see figure 5 in ( 1 )]. The authors ( 1 ) interpretation of this latter finding is that recurrences after radiation are less frequent but tend to be more aggressive. Whether these tumors represent radiation-induced second malignancies as previously suggested ( 3 ) cannot be excluded.