Seventy years ago, before breast cancer screening with mammography made early detection the norm, women were often diagnosed with large tumors that had invaded the skin or chest wall. Worldwide, such "locally advanced" cancer still accounts for about 60 percent of cases.
These days in the U.S., however, only about 5 percent of breast cancers are locally advanced. Bleicher, a breast cancer specialist, said his department may see a couple of cases a year.
"But these are usually women with tiny, superficial skin lesions, and they do quite well," he said. "Classifying them as stage III just seemed wrong."
Staging - that is, determining the extent of cancer in the body - is done to estimate survival odds, and to help plan treatment.
To evaluate the current staging of women with skin involvement, Bleicher and colleagues analyzed a federal cancer surveillance database, and Medicare claims, from 1992 to 2005.
Of 66,185 women age 65 and over with breast cancer, only 924, or 1.4 percent, had skin involvement. In theory, that meant their chances of surviving five years was 40 percent to 67 percent, which is the overall prognosis for stage III.
But when the researchers reclassified those 924 women based only on the size of their tumors and lymph node status, 43 percent of them fell into earlier stages. More important, the five-year survival of this subset of women was just as good as early-stage women who had no skin involvement - as high as 96 percent.
Evaluating whether such women were appropriately treated was more difficult because care standards have evolved since the 1990s, and the data did not distinguish between chemotherapy given before or after surgery. Traditionally, women with skin involvement automatically got chemotherapy first, then underwent mastectomy.
"It was almost random when we looked at the [treatment data]," Bleicher said. "That suggests clinicians are trying to grapple with how to deal with these" small, breast-confined tumors that involve the skin.
The study concluded the staging criteria needs to be revised to reflect current realities. That, Bleicher said, may happen soon: One of the experts who edited the paper said it would be helpful to the American Joint Committee on Cancer, a group of experts who will meet this summer to review the classification system.