Tumor response may not be best measure of efficacy in non-small cell lung cancer treatment

Findings have broad implications for design of clinical trials for advanced NSCLC

Researchers typically evaluate the effectiveness of a new cancer treatment by looking at how tumors respond to it. But in the case of advanced non-small cell lung cancer, there may be a better way to assess effectiveness.

A new Southwest Oncology Group study led by a team of UC Davis Cancer Center researchers suggests that an alternative measurement – “disease control rate” – may be a more powerful predictor of survival than tumor shrinkage. The research was presented today at the annual meeting of the American Society of Clinical Oncology in Atlanta.

“If validated, this ’early look’ statistical measure could enhance efficacy assessment, with broad implications for the design of future cancer clinical trials for advanced non-small cell lung cancer,” said Primo N. Lara, Jr., associate professor of hematology and oncology at UC Davis Cancer Center and lead author of the new study.

Lara and his colleagues defined the disease control rate as the percentage of patients who have a partial or complete response to an investigational treatment plus those whose disease stabilizes.

“In the past, we have used the complete response rate plus the partial response rate, or CR + PR, as our sole efficacy measure,” Lara said. “The disease control rate, DCR, is the complete response rate plus the partial response rate plus the rate of patients with stabilized disease, or DCR = CR + PR + SD. This measure may better predict how a new drug will affect survival.”

In their study, the investigators pooled data from 984 patients with advanced non-small cell lung cancer who participated in three randomized SWOG trials of platinum-based chemotherapy regimens.

Of the 886 patients who were alive two months after beginning treatment, 62 percent had stable disease, meaning their cancer had not progressed since entering the clinical trial. Another 19 percent had a complete or partial response, meaning their tumors had disappeared or reduced in size. Adding the two measures together yielded a disease control rate of 81 percent.

When Lara and his colleagues compared the disease control rate to the standard measure (CR+PR), they found that the disease control rate had a much stronger association with survival.

“The cancer community is actively looking for ways to improve clinical trials, so that we can get better answers more efficiently and bring advances to our patients more rapidly. Nowhere is this more important than in lung cancer,” Lara said. “These findings will be prospectively tested in SWOG, but if they bear out, they may help us to design smarter clinical trials for lung and perhaps other cancers.”

Lung cancer is the leading cause of cancer death among both men and women in the United States. According to the American Cancer Society, an estimated 174,470 people will get lung cancer this year, and 162,460 will die from it. Non-small cell lung cancer accounts for about 80 percent of lung cancer cases.