Invasive local recurrence increased after radiation therapy for ductal carcinoma in situ.

Background: It is thought that equal numbers of invasive and noninvasive recurrences develop after conservative treatment for ductal carcinoma in situ. We analyzed our data to see if this was true.

Methods: A prospective database of 878 conservatively treated patients with ductal carcinoma in situ was analyzed.

Results: Among 551 excision patients, there were 88 recurrences. Thirty-five percent were invasive. Among 327 excision plus radiotherapy patients, there were 59 recurrences. Fifty-three percent were invasive. In an attempt to predict which patients develop invasive recurrences, prolonged time to recurrence was the only statistically significant factor.

Conclusions: The median time to local recurrence for irradiated patients was more than twice as long when compared with nonirradiated patients, during which there is more time for local recurrence to progress to invasion. Irradiated patients had more breast scarring, making diagnosis by palpation and mammography harder. Irradiated patients develop invasive recurrences at a statistically higher rate than nonirradiated patients. Follow-up evaluation with magnetic resonance imaging should be considered.