The value of radiation therapy after excision of stage I breast cancer.

Most studies of the treatment of early breast cancer with conservative surgery and radiation therapy have had two major shortcomings: they have been based largely on short-term follow-up; and they have compared their short-term results only with long-term results after mastectomy. These methods greatly underestimate the actual incidence of local recurrence after breast preservation combined with radiation therapy because a significant portion (50% or more) of local recurrences after radiation treatment for early breast cancer are recognized more than five years after treatment. The effect of radiation is more accurately assessed by comparing results with conservative surgery without radiation therapy. This allows an estimate of the effect of the radiation therapy itself. Ten-year local recurrence rates after treatment of early breast cancer with mastectomy, conservative surgery with radiation therapy and conservative surgery without radiation therapy are 0-8%, 13-26% and 16-19% respectively. When breast preservation is combined with radiation therapy there is a lower incidence of local recurrence at five years, but at 10 years the results with and without radiation therapy are quite comparable. In both situations the recurrence rates are much higher than after mastectomy. The significance of this higher recurrence rate has not been fully evaluated. All reports of the treatment of early breast cancer should have at least 10 years of follow-up. Under no circumstances should any data be published which include patients followed for less than five years.