The antitumor activity of radiation therapy is reduced in patients with non-small-cell carcinoma of the lung refractory to chemotherapy.
Some in vitro studies demonstrate cross-resistance between chemotherapy (CT) and radiation therapy (RT) but there is no in vivo data showing the same effect. Several studies have estimated the response rate to chemotherapy following radiation, but the question of radiation responsiveness in chemotherapy-refractory tumors has not been examined. Between 1982 and 1988, 162 patients with stage IIIA, IIIB and IV non-small-cell lung cancer (NSCLC) received chemotherapy on various protocols at the National Cancer Center. All were treated until progression or the occurrence of unacceptable toxicity. Forty patients developed local progression on chemotherapy and were given radiation therapy (50 to 60 Gy). Nine responders (22.5%: 95% confidence limit, 9.5-35.5%) were seen in this group, a rate substantially lower than was to be expected with primary radiation treatment. The univariate logistic regression analysis with RT response as the outcome demonstrated that there was significant heterogeneity in response for T and N status between responders and non-responders. Also the odd ratio for radiation dose was strong (OR = 0.20), indicating that a low dose was less likely to produce response although this was not statistically significant. Hematologic toxicity was mild, but 11 patients (27.5%) developed evidence of acute radiation pneumonitis. These results suggest that some chemotherapy-refractory NSCLC may show cross-resistance to radiation therapy which consequently has marginal antitumor activity in this setting.
Morita
M
M
National Cancer Center Hospital, Tokyo, Japan.
Sasaki
Y
Y
Saijo
N
N
D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011878:Radiotherapy / Q000009:adverse effects