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Mixed Recurrence Outcomes When Radiation Is Added to Excision for DCIS
Elsevier Global Medical News. 2011 May 9, MG Sullivan
WASHINGTON (EGMN) - Five years might not be the magic number for a small group of women who are treated for the most curable form of breast cancer: ductal carcinoma in situ.
In a prospective study, women who underwent excision plus radiotherapy did have a significantly lower rate of local recurrence than did women who were treated with surgery alone. But among those who had a recurrence, it was almost twice as likely to be invasive. Additionally, these recurrences took almost twice as long to present: up to 105 months.
"This shows there is definitely an added benefit from radiation, but at the same time, we must be aware that patients who have radiation can still recur, and much later," Dr. Janie Weng Grumley said at a press briefing during the annual meeting of the American Society of Breast Surgeons.
"Many patients think, 'after 5 years, I'm safe.' This study really highlights the fact that there is a very different pattern of recurrence [in those who receive one of the two treatments]. We must be aware of this, and follow these women in a different way."
Dr. Grumley, a fellow at the University of Southern California in Los Angeles, presented a prospective study of 1,014 women with ductal carcinoma in situ (DCIS) who were treated with either excision alone (651) or excision plus radiotherapy (363). The average follow-up was significantly longer in the dual-therapy group (average, 109 months) than in the excision-only group (average, 72 months), reflecting the recent increase in lumpectomy-only treatment, Dr. Grumley said. The groups' average age was 54 years.
The probability of any local recurrence was significantly lower in the dual-therapy group than in the lumpectomy group (18% vs. 30%; P = .0102). But invasive disease was significantly more common among those in the dual-therapy group who did recur (57% vs. 37%). The cancers also took significantly longer to recur, whether the study examined the mean time to any local recurrence (90 vs. 53 months; P less than or equal to .001), the mean time to DCIS recurrence (73 vs. 41 months; P = .002), or the mean time to invasive recurrence (105 vs. 72 months; P = .017).
Women who had surgery and radiation also experienced a significantly different pattern of recurrence, Dr. Grumley said. Among women treated only with surgery, 90% of recurrences were in the same quadrant, compared with 72% of recurrences in women who were treated with dual therapy (P = .0016). Conversely, 28% of recurrences after dual therapy occurred in a different quadrant, compared with 10% of those in the surgery-alone group. Lesions in different quadrants likely reflect new primary tumors, she said.
The increased rate of invasive, recurrent disease in the dual-therapy group was probably responsible for a small but statistically significant mortality difference (98% vs. 100%), Dr. Grumley said.
"This study shows that a small subgroup of irradiated DCIS patients may not be deriving maximum benefit from radiation therapy, or not benefiting from it at all," she said.
She was only able to speculate on the reason for the different recurrence patterns. "Radiation is a hypothesis, but we have nothing here that we can connect [as a] cause and effect. We do know that radiation does affect local recurrence, and we would never tell a patient not to get radiation. But this pattern is definitely something that should be further examined.
Dr. Grumley had no financial conflicts to declare.
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