Effects of ongoing smoking on the development of radiation-induced pneumonitis in breast cancer and oesophagus cancer patients

Abstract

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.

Introduction

Tobacco is one of the major toxic agents in our civilization. Cigarette smoking is a carcinogenic factor leading to several cancers, such as tumours of the lungs, oesophagus and head and neck region. In sharp contrast, inflammatory diseases of the lungs, like sarcoidosis and extrinsic alveolitis, and also other inflammatory diseases, such as ulcerative colitis, occur less frequently in smokers than in non-smokers 1, 12, 26.

Radiation-induced pneumonitis and fibrosis are complications that may arise in the lung after irradiation of any kind of malignant disease in the thorax, such as radiation treatment after breast cancer surgery and as a primary treatment for oesophagus cancer patients. We have earlier studied the inflammatory process of the lung tissue in bronchoalveolar lavage (BAL) after radiation treatment of breast cancer patients. Ongoing smoking seemed to suppress the early inflammatory reactions in BAL after radiation treatment 3, 4 and these data have been confirmed by experimental studies on animals as well [23]. As far as we know, radiation-induced pneumonitis has not previously been evaluated in oesophagus cancer patients.

Acute clinical radiation pneumonitis develops in 5–15% of the patients receiving radiation therapy to the chest and is characterized by the insidious onset of fever, exertional dyspnoea and non-productive cough 6–12 weeks after the end of radiation therapy, although cases have been reported as early as 2 weeks after irradiation [9]. An infiltrate is usually seen in the treatment field on the chest radiograph. Pulmonary function tests (PFT) may show reduced lung volumes, impaired gas exchange, hypoxia and compensatory hypocapnia [9]. Although details of the cellular mechanisms by which the acute changes in the lungs occur are unclear, an increase of lymphocytes and mast cells in BAL have been observed in irradiated patients [3]. This might indicate an immunologically mediated mechanism either in response to or because of direct lung injury in the treatment field 9, 10, 25.

These previous results make it interesting to study the interaction of smoking and irradiation in a larger group of patients.