Purpose: To assess the genuineness and curability of diagnosed cases of Stage IA non-small-cell lung cancer of diameter 6-15 mm, with a view to screen-diagnosed asymptomatic cases.
Methods: We identified all cases of diagnosed Stage IA (T1N0M0) primary non-small-cell lung cancer documented in the Surveillance, Epidemiology, and End Results (SEER) registry in 1988-1994. There were 885 such cases of diameter 6-15 mm, 33 of them unresected, 1659 of diameter 16-25 mm, and 782 of diameter 26-30 mm. We determined the 8-year cumulative lung-cancer death rates adjusted for competing causes of death, separately for untreated and fully resected cases. Given the relative underdetection of lymph node metastases of the untreated cases, we also documented the case-fatality rates for the resected with inclusion of those with detected intra-pulmonary, hilar or ipsilateral mediastinal lymph node metastases.
Results: The 8-year fatality rate for the diagnosed but untreated cases of lung cancer 6-15 mm in diameter was 87%, for 16-25 mm it was 94%, and for 26-30 mm it was 88%. The corresponding estimates of cure rates with resection were 71, 67, and 55%, respectively. The cure rate estimate for the smallest cancers was 66% when adding those with detected lymph node metastases to the resected series, for those 16-25 mm in diameter it was 65%, and for those 26-30 mm in diameter it was 51%.
Conclusion: Almost all diagnosed cases of Stage IA lung cancer as small as 10 mm in diameter have a malignant natural course, fatal if not treated, thus representing genuine cancer. Most of these cases are curable by resection.