Background and aim: New treatment regimens require a differentiation between histological subsets of non-small cell lung cancer. We aimed to assess how the incidence and prognosis of carcinoma not otherwise specified (NOS) coincide with an aging patient population, disease stage, and diagnostic methods used.
Methods: Complete national data on 40,118 cases (including 6,597 diagnosed with carcinoma NOS) from the Cancer Registry of Norway (1988-2007) are presented.
Results: The proportion of elderly patients (70 years and older) have increased to over half of all patients diagnosed, a trend also evident among carcinoma NOS patients. The proportion of carcinomas NOS reported to the cancer registry in this 20-year period has increased from 12% in 1988 to 19% in 2007. Crude 5-year relative survival in carcinoma NOS was lowest of all non-small cell lung cancer entities throughout the 20-year period; however, patients diagnosed with carcinoma NOS in the period 2003 to 2007 had about 24% lower risk of dying within 5 years after diagnosis compared with patients diagnosed between 1988 and 1992, adjusted for covariates. Most lung cancers are diagnosed by biopsy of the primary lesion; although the proportion is lower among carcinomas NOS than other histological entities. By the last 5-year period studied, carcinoma NOS was the histological entity most commonly diagnosed by cytology (38%).
Conclusion: The proportion of carcinomas NOS has increased to 19% of all lung cancer cases. This histological entity is associated with older age and poor survival.