Most patients with advanced urothelial carcinoma who had disease control after 4 cycles of first-line chemotherapy did not have a >10% reduction in tumor size when they received an additional 2 cycles of chemotherapy, according to a recent study.
Akihiro Hamada, MD, of the Kyoto University Graduate School of Medicine, and colleagues conducted the retrospective study to “investigate the correlation between tumor size changes during the initial 4 cycles of first-line chemotherapy and tumor shrinkage following 2 additional cycles of chemotherapy in patients with advanced urothelial carcinoma who experienced disease control after initial chemotherapy.” They published the study’s results in Urologic Oncology: Seminars and Original Investigations.
Dr. Hamada and colleagues reviewed data from 128 patients with advanced urothelial carcinoma who received first-line chemotherapy. They analyzed 51 patients who had disease control, defined as stable disease or better, at the end of the fourth chemotherapy cycle. Most of those 51 patients (92.1%) underwent 1 to 2 additional chemotherapy cycles, while the remaining 7.9% underwent observation.
The researchers defined 4 categories to describe the tumor size changes in patients who received 1 to 2 more additional chemotherapy cycles. The categories were “no shrinkage,” defined as tumor growth; “minor shrinkage,” defined as no tumor growth or a ≤10% reduction in tumor size; and “shrinkage,” defined as a >10% reduction in tumor size.
Dr. Hamada and colleagues categorized the change in tumor size as “no shrinkage” in 44.7% of patients, “minor shrinkage” in 38.3%, and “shrinkage” in 17%.
The rate of tumor size change between cycles 3 and 4 was significantly associated with the trend of tumor shrinkage (P=.009) and the “likelihood of beneficial tumor shrinkage” after additional chemotherapy (P=.02), according to the researchers.
“However, the change in tumor size between cycles 1 and 2, cycles 1 and 4, or cycles 3 and 4 was not satisfactorily predictive of further tumor shrinkage because of substantial overlaps of the tumor size changes,” Dr. Hamada and colleagues wrote.
The results of the research may inform treatment approaches to advanced urothelial carcinoma, according to the researchers.
“Only a small subset of patients would have substantial tumor shrinkage by additional cycles after successful induction of 4-cycle chemotherapy. Tumor size dynamics during the initial 4 cycles of chemotherapy displayed limited ability to predict the subset of patients with further tumor shrinkage after additional chemotherapy,” Dr. Hamada and colleagues concluded. “Therefore, it might be better to consider switch maintenance immunotherapy for patients who experience disease control after the fourth cycle of first-line chemotherapy.”