Purpose: To investigate the influence of smoking on the development of radiation-induced pneumonitis in patients treated for breast and oesophagus cancer.
Materials and methods: This is a retrospective study on 405 females diagnosed with primary unilateral breast cancer stages 1 and 2 and 201 oesophagus carcinoma patients. The possibilities in Sweden to obtain detailed information from different medical records were used to collect data on smoking habits, radiation treatment and spontaneously reported pneumonitis. Radiation-induced pneumonitis was defined as a combination of roentgenographic infiltrate in the lung field involving an irradiated area on the chest X-ray and clinical symptoms such as non-productive cough and dyspnoea.
Results: Six breast cancer patients had spontaneously reported pneumonitis. Five of them were non-smokers (P = 0.182) and the other was a former smoker. Eight of the oesophagus cancer patients had spontaneously reported radiation-induced clinical pneumonitis and they were all non-smokers (P = 0.022), except one, who was a pipe smoker. None of the patients who were cigarette smokers were recorded as developing clinical pneumonitis after irradiation.
Conclusion: These data could support the previous clinical observations and experimental studies that smoking depresses the frequency of radiation-induced pneumonitis. The present study as well as earlier observations could justify further studies concerning the possibility of an interaction of smoking with cancer treatment, both from the view of therapeutic failures and reduced adverse effects.