Trends in lung cancer incidence by histologic subtype in the south of Spain, 1985-2012: a population-based study

To analyze and interpret age- and sex-specific incidence trends of lung cancer in Granada over the period 1985-2012 and to further analyze these trends by histologic subtype.

Incidence data were obtained from the population-based cancer registry located in Granada (Southern Spain). All cases with newly diagnosed primary lung cancer over the period 1985-2012 (n = 8658) and defined by International Classification of Diseases 10th Revision (codes C33-C34) were included. Joinpoint regression analysis of age-standardized incidence rates was used to estimate the annual percent change (APC) and 95% confidence intervals. Results are presented overall and by sex, age groups (0-34, 35-54, 55-64, 65-74, ≥75 years) and histologic subtypes.

Temporal trends of incidence rates by sex, over the period 1985-2012, showed a distinct pattern. A significant change point of the trend was observed in males in 1994 (APC: +2.5%; 95% CI 0.7-4.4 from 1985 to 1994 and -1.4%; 95% CI -2.0 to -0.7 from 1994 onward). This general change was mainly caused by the age group 65-74 years and by the higher incidence of squamous cell carcinoma histologic subtype. In females, lung cancer incidence increased over the entire study period by +4.2% per year (95% CI 3.1-5.4); this trend was mainly caused by the age group 55-64 years (APC = +7%) and by adenocarcinoma incidence between women (APC = +6.8%).

Male lung cancer incidence rates have decreased in Granada, while female rates have increased overall especially in younger women. These trends may reflect the increased consumption of cigarettes in women, especially during younger ages. Lung cancer prevention through tobacco control policies are therefore of utmost importance.