Objective: To analyze chest radiographic patterns of lung cancer at presentation by cell type. This current series is compared with historic published data.
Design: Retrospective, using a tumor registry.
Setting: Large, rural multispecialty clinic.
Patients: Three hundred forty-five patients with newly diagnosed lung cancers presenting between October 1990 and August 1992.
Methods: Radiographs were interpreted by two radiologists blinded to cell type. Our results were compared statistically to published data from Mayo Clinic patients in the 1950s and 1960s.
Results: Adenocarcinoma: Decreased presentation as a peripheral tumor in current series (49%) compared with historic control at Mayo (72%); squamous cell: increased presentation as peripheral tumor in current series (43%) compared with historic control (31%); and no statistically significant difference between adenocarcinoma (49%) and squamous (43%) for a presentation as a peripheral mass, or between adenocarcinoma (46%) and squamous (52%) for central origin in the current series of cases.
Conclusion: As adenocarcinoma has increased in relative frequency among lung cancers, the percent of cases with peripheral primary tumors is decreased while central tumors have increased. Squamous carcinoma has had a relative increase in peripheral mass presentation. There is now no significant difference between these two cell types in percent presenting as a peripheral mass or central tumor on chest radiograph.
Chest radiography remains the basic imaging modality for the detection of lung cancer. Recent textbooks and articles continue to use the radiographic pattern as a clue to cell type.” Much of the reference data comes from a comprehensive review by the Mayo Clinic published in 1969 and represents lung cancer in an earlier era.
Patients in the Mayo Clinic series were all seen prior to 1966, with most cases from 1954 through 1957. Since that time, there have been several changes in the demographics of lung cancer patients and the relative incidence of cell types.
First, there has been a marked increase in the incidence of lung cancer in women.’ Second, since the 1950s, there has been a shift in the relative frequency of cell types. Currently, adenocarcinoma is the most common cell type of bronchogenic carcinoma in the United States. Squamous cell cancer has fallen to number two in incidence, having previously been the most common cell type.”
In view of these changes in lung cancer during the last 30 years, we thought it would be worthwhile to re-examine cell type in relation to chest radiograph at presentation. We used a contemporary series of patients to compare statistically with the earlier Mayo Clinic series.