- The Washington Times - Tuesday, August 9, 2005

The odds of surviving breast cancer have improved in recent years, not only because treatments are so much better, but also because the average tumor is smaller, a major new study shows.

Examining 25 years of cancer records nationwide, researchers concluded that smaller tumor size accounted for 61 percent of the improvement in survival when cancer had not spread beyond the breast, and 28 percent when it had spread just a little.

For women 65 and older with early-stage tumors, the most common scenario, the shift in size accounted for virtually all of the improvement in survival.

“We don’t in any way want to diminish the benefits we’ve seen from advances in treatment, because they’ve been enormous,” said lead researcher Elena Elkin. “But not all of the improvement in survival is due to treatment when important characteristics like size have also changed over time.”

The study wasn’t designed to determine the value of mammograms or treatments, but it implies much about the value of early detection.

“This really helps to show the importance of screening,” said Debbie Saslow, who heads breast cancer research at the American Cancer Society. “In addition to finding more small tumors, we’re also finding less big tumors.”

Miss Saslow had no role in the study. It was conducted by doctors at Memorial Sloan-Kettering Cancer Center in New York and used a federal government database that includes nine cancer registries covering 10 percent of the U.S. population.

Breast cancer is the most common cancer in American women. An estimated 211,240 new cases and 40,400 deaths from it are expected this year.

Survival has increased, but experts have argued over how much of that is because of better drugs or tumors being found at earlier stages. Two-thirds of breast cancers today are diagnosed at the local stage.

“Even within the same stage category, the average tumor size is smaller today than it was 25 years ago,” Miss Elkin said.

For example, the number of local-stage breast cancers that were smaller than 1 centimeter rose from less than 10 percent from 1975 through 1979 to 25 percent from 1995 through 1999. An inch is about 2.5 centimeters.

Of regional-stage cancers — those that spread to nearby tissue or lymph nodes, but not widely throughout the body — the portion that were smaller than 2 centimeters rose from one-fifth to one-third.

Next, researchers compared five-year survival rates for these time periods, taking into account the shift in tumor size.

For women with local-stage breast cancers, survival rose from nearly 91 percent to more than 97 percent, but was only 93 percent after adjusting for smaller tumors. Looked at another way, the shift in size accounted for 61 percent of the improvement in survival.

For regional cancers, survival rose from about 68 percent to about 80 percent, but was only 76 percent once tumor size was factored in.

Size made a much bigger difference for older women than younger ones. A whopping 96 percent of the survival improvement for women 65 and older with local-stage cancers was explained by this. Only 38 percent of the improvement in women under 50 was a result of the shift in tumor size.

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