Occult micrometastasis to bone marrow in early lung cancer: a clinicopathologic study from West Bengal, India.

Although bone marrow micrometastasis may remain silent, its detection changes the staging and management of lung cancer. In the present study conducted in West Bengal, India, 74 diagnosed bronchogenic carcinoma cases (28 squamous cell carcinomas, 20 adenocarcinomas, 9 small cell carcinomas, 4 large cell carcinomas, 13 unclassified) in early stages (stage I, II and IIIA) were included. Complete hemograms, bone marrow aspiration and cell blocks of aspirated material, trephine biopsy were done for detection of micrometastasis. Overall micrometastases in bone marrow were noted in 17 cases (23.0%). We detected marrow metastasis in 44.4% cases of small cell carcinomas and 21.2% cases of non small cell lung cancer (50% of large cell carcinomas, 20% of adenocarcinomas, 17.9% of squamous cell carcinomas) and 15.4% cases of unclassified carcinoma. We found a statistically significant correlation between marrow metastasis and low platelet count (P=0.0001) and high ESR (P=0.0003), but no significant correlation with hemoglobin percentage (P=0.36), total leukocyte count (P=0.58) and eosinophil count (P=0.44). A definite correlation noted between micrometastasis with the clinical stage (no case in Stage I, 12.5% in Stage II, 30.4% in Stage IIIA patients). We emphasize that detection of micrometastasis is essential particularly in non small cell cancers, where treatment with curative intent is planned, which can be suitably done by morphological study of bone marrow aspirate and biopsy in countries like India.