LOS ANGELESSurgical margin width offers a reasonable prognostic surrogate for the more complicated multiparameter Van Nuys Prognostic Index to predict breast cancer recurrence after treatment for ductal carcinoma in situ (DCIS), but the index still provides superior accuracy, Melvin J. Silverstein, MD, of the University of Southern California, said at the San Antonio Breast Cancer Symposium.
He said that the index should be superior because it incorporates four factors (tumor size, biologic classification based on tumor grade and necrosis, and excision margin width), but it is clearly more difficult to use.
In 1999, Dr. Silverstein and his colleagues published a paper advocating the use of margin width as the sole determinant of treatment for DCIS (N Engl J Med 340:1455-1461, 1999). Afterwards, the group was inundated with questions about whether to abandon the Van Nuys Prognostic Index, Dr. Silverstein said. This led the researchers to compare the prognostic value of the index vs surgical margins alone in DCIS patients.
A surgical margin of greater than 10 mm was associated with a 12-year recurrence-free survival of 96%, compared with 99% for patients with a score of 3-4 (the best possible score) on the index. The difference did not achieve statistical significance but showed a trend in favor of the index.
The data came from an evaluation of 523 DCIS patients treated by breast-conserving surgery (with or without radiation therapy). A total of 88 local recurrences have been documented, 41 invasive cancers and 47 DCIS recurrences. All but seven recurrences were at or near the site of the primary lesion, suggesting inadequate surgery, he said.
There was a single recurrence of DCIS associated with an index score of 3-4. Five recurrences were observed in patients who had wide margins, but two recurrences were invasive and one patient had metastatic disease and subsequently died. At the other end of the spectrum, an index score of 8 or 9 was associated with poorer outcomes than was the single prognostic factor of narrow surgical margins.
Dr. Silverstein stressed that the index remains the preferred method at his institution. The best possible score on the index is 3 (low biologic classification, small size, wide margins), while the worst is 9 (large, poorly excised tumor with a high biologic classification). His analyses have shown that DCIS patients with a score of 3-4 derive no benefit from radiation therapy; a score of 5-7 is associated with a 15% benefit from radiation therapy, and a score of 8-9 with a 30% benefit.
His group recommends excision alone for DCIS patients with scores of 3-4, excision plus irradiation for those with scores of 5-7, and mastectomy for patients with scores of 8-9.