Interstitial Pulmonary Fibrosis and Lung Cancer

Abstract

Diffuse interstitial pulmonary fibrosis (DIPF), the prototypic restrictive lung disorder, has been long recognized as a chronic inflammatory process characterized by abnormal collagen deposition.1Crystal RG Fulmer JD Roberts WC et al.Idiopathic pulmonary fibrosis: clinical, radiographic, physiologic, scintigraphic, cytologic, and biochemical aspects.Ann Intern Med. 1976; 85: 769-788Crossref PubMed Scopus (499) Google Scholar In the majority of cases, the cause of DIPF remains idiopathic—Scadding's “cryptogenic fibrosing alveolitis.2Scadding JG Fibrosing alveolitis.BMJ. 1964; 686: iiGoogle Scholar In this issue of CHEST, Mizushima and Kobayashi (see page 1272) present an exhaustive review of the Japanese literature on DIPF patients who have developed lung cancer. Their primary intent was to identify clinical and pathologic characteristics of multicentric bronchogenic carcinomas, of both synchronous and metachronous varieties3Rohwedder JJ Weatherbee L Multiple primary bronchogenic carcinoma with a review of the literature.Am Rev Respir Dis. 1974; 109: 435-445PubMed Google Scholar in this population. This was accomplished by comparison of the multicentric tumor group, with that of DIPF patients with cancer of a solitary lung, and of a massive historic group of bronchogenic carcinomas of all types in Japanese patients.4Yoshimura K Yamashita N Clinical statistical observation of 4931 cases with lung cancer by histological types: result of field study in Japan [Japanese].Lung Cancer. 1982; 22: 1-16Google Scholar Perhaps the most important message conveyed by this scholarly and encyclopedic review is not that of the particular clinical features and cell types of these rare multicentric tumors in DIPF patients. Since the classic description of the association of lung cancer with cryptogenic fibrosing alveolitis by Turner-Warwick et al, there has been too little attention given to the potential in this setting for development of this usually fatal neoplasm. Most current epidemiologic treatises on predisposing conditions for lung cancer give minor discussion, inferring questionable acceptance, of the important risk factor of underlying DIPF. Comments are frequent regarding potential for malignant transformations in interstitial fibroses of known etiology such as pulmonary asbestosis and “scleroderma lung,” yet the inherent danger in the most common of interstitial disorders, that of the idiopathic variety, is largely ignored. In the Mizushima and Kobayashi article, we are reminded of the difficulty of identifying lung cancer in DIPF patients because of its usual peripheral location and preference for the lower lobes, where the chronic inflammatory process is most evident radiographically. As opposed to the rare “scar carcinoma” described by Auerbach et al6Auerbach O Garfinkel L Parks VR Scar cancer of the lung: increase over a 21 year period.Cancer. 1979; 43: 636-642Crossref PubMed Scopus (109) Google Scholar as developing in localized underlying conditions such as infarcts or granulomas, and usually of adenocarcinoma type, the frequency distribution of cell types in DIPF patients is similar to that of the “universe” of lung cancer. Additional to problems in diagnosis of bronchogenic carcinoma in this setting are the management complications imposed by decreased potential for surgical excision due to major underlying impairment of pulmonary function, and the predictable chronic toxicity of therapeutic irradiation with preexistent diffuse pulmonary fibrosis. In patients with DIPF, our most important tools are: (1) prevention relative to the usual causative agent of lung cancer—cigarette smoking, which was highly prevalent in this present report, and (2) vigilant screening,7Haddad R Massaro D Idiopathic diffuse interstitial pulmonary fibrosis (fibrosing alveolitis), atypical epithelial proliferation and lung cancer.Am J Med. 1968; 45: 211-219Abstract Full Text PDF PubMed Scopus (84) Google Scholar by clinical and roentgenographic means, in this special high-risk population.