Purpose: To evaluate the impact of the cigarette burden (CB) on the response rate to platinum-based chemotherapy (CT) in patients with lung cancer (LC).
Methods: Retrospective study of patients with LC treated by CT from 2000 to 2005, in a tertiary referral center in Brazil. The CB was measured by the number of pack-years smoked (PY). To evaluate the response (by RECIST), it was necessary to accomplish two cycles of CT. The relevant variables were studied by univariate and multivariate statistical techniques.
Results: Two hundred and eighty-five patients (203 men) were studied (mean age=60.6+/-10.1 years, mean PY=58.3+/-35.4). 62.8% were current smokers, 26.7% were former smokers, and 10.5% were non-smokers. 63.2% had non-small-cell lung cancer (NSCLC), and 36.8% had small-cell lung cancer (SCLC). The treatment intent was palliative in 63.9% and curative in 36.1%. All 285 patients received platinum-based CT (etoposide/cisplatin in 68.8% and etoposide/carboplatin in 31.2%). Of these, 155 patients (54.4%) received RT (median dose=50.0 Gy; range=45.0-80.0). The 94 patients (33.0%) who responded to treatment had a mean PY of 38.7+/-27.1, and the 191 patients (67.0%) who did not respond had a mean PY of 67.8+/-35.1, p<0.001. In the multivariate analysis, the main independent negative predictor was CB>or=40 PY (adjusted OR=10.42; 95% CI=5.13-21.28). The others independent negative predictors were: CT (no. of cycles=2-4) (adjusted OR=4.86; 95% CI=2.44-9.68), treatment regimen with CT alone (adjusted OR=3.38; 95% CI=1.67-6.84), and NSCLC histology (adjusted OR=2.75; 95% CI=1.12-6.76).
Conclusion: Patients with CB>or=40 PY have a worse response to platinum-based CT compared to those who have a CB<40 PY.