Timing radiotherapy

This study compared the effectiveness of radiotherapy started at different times during the treatment of small-cell lung cancer.

Treatment of small-cell lung cancer often includes a combination of chemotherapy and radiation therapy. However, the optimal timing of radiotherapy is still a matter of some debate. When started with or before chemotherapy, radiotherapy may cause adverse effects which may necessitate a delay in chemotherapy treatments. Radiotherapy can instead be started at a late chemotherapy cycle, meaning that the completion of chemotherapy would not be interfered with, even if adverse effects occur. However, whether radiotherapy is as effective when started at a later chemotherapy cycle is unclear. Previous studies examining this question have reported inconclusive results.

219 patients were randomly assigned to receive radiation therapy with either their first chemotherapy cycle (early group) or their third chemotherapy cycle (late group). Overall, all patients underwent four chemotherapy cycles, each lasting three weeks. Complete response to treatment (as measured by tumor shrinkage), progression-free survival (the time between treatments and progression of the disease) and overall survival were measured.

The complete response rate was similar in both early and late treatment groups. 36% of patients in the early group showed complete response to treatments, compared to 34% in the late treatment group. Achieving complete response to treatment was associated with an 11 month increase in overall survival compared to patients not achieving complete response to treatment. Progression-free survival and overall survival were also found to be similar in the two treatment groups. Disease progression was seen on average 12.4 months after treatments in the early group, and after 11.2 months in the late group. On average, overall survival was 24.1 months in the early group and 26.8 in the late group. On statistical analysis accounting for multiple variables none of these differences were found to be significant. Neutropenic fever (a rising body temperature in a patient with a low white blood cell count. A common and dangerous side effect of cancer treatments indicating an infection that the body cannot fight on its own) occurred more commonly in the early treatment group. 21.6% of patients in the early treatment group experienced neutropenic fever, compared to only 10.2% of patients in the late treatment group.

This study concluded that radiotherapy begun on a later chemotherapy cycle is as effective as radiotherapy started on the first chemotherapy cycle. Late radiotherapy seems to be associated with a reduced risk of neutropenic fever.