Jacqui Tan, MD OncoLink Assistant Editor Last Modified: November 1, 2001
Presenter: E. Obedian Affiliation: Yale University School of Medicine
Summary: Multiple studies have demonstrated the clinical efficacy of breast conserving therapy (BCT) for early stage breast cancer. Despite decades of experience, however, there are limited data regarding the safety of this treatment, specificially the risk of second malignancy.
The records of 1029 patients undergoing lumpectomy and radiation therapy (BCT) were compared with those of 1387 patients undergoing mastectomy (MAST) from January, 1970 to December, 1990.
Charts were reviewed with attention to second malignancies (contralateral breast vs. non-breast), age, stage, history of tobacco use, radiation technique, dose, and systemic treatment.
Ipsilateral tumor was scored as a recurrence, and lobular carcinoma in situ was excluded from analysis.
The median follow-up period was 14.6 years for the BCT group and 16 years for the MAST group.
158 contralateral breast cancers and 164 non-breast cancers (mostly gastrointestinal and gynecologic malignancies) occurred in the group as a whole.
The 15 year risk of a second malignancy was 17.5% for BCT patients and 19% for MAST patients (NS).
Patients who developed a second malignancy had a significantly decreased survival (55 vs. 69% at 15 years).
The only factor predictive of a second malignancy was tobacco abuse.
Despite the potential carcinogenic risk associated with breast irradiation as a component of BCT, there is no evidence of an increased rate of second malignancy in this study.
Because the latency of radiation-induced malignancy can be more than 8-10 years, though, further follow-up is warranted.
What is clear from these data, as well as from myriad other sources, is that patients who smoke tobacco should stop.
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