Lung cancer with gastrointestinal metastasis - review of theories of metastasis with three rare case descriptions.

Approximately 1 in 14 men and women during their lifetime will be diagnosed with lung cancer, which is the leading cause of cancer-related mortality in the world. As of January 1, 2008, there were about 373,500 men and women living with lung cancer in the United States. Fewer than 60,000 of these are estimated to be alive by January 2013, reflecting a poor overall 5-year relative survival rate of under 16 %. With metastatic cancer, the overall 5-year survival is meager 4 %. On the other hand, the overall five-year survival is over 50 % when the cancer is still in the localized stage. However, unfortunately, more than half of cases of lung cancer are diagnosed at an advanced stage Howlader et al. (2010). Cancer metastasis, the single most critical prognostic factor, is still poorly understood and a highly complex phenomenon. The most common sites of lung cancer metastasis are the lymph nodes, liver, adrenals, brain and bones. The gastrointestinal (GI) tract is an exceptionally rare site of metastasis; with only a handful of cases reported in the literature Centeno et al. (Lung Cancer, 18: 101-105, 1997); Hirasaki et al. (World J Gastroenterol, 14: 5481-5483, 2008); Carr and Boulos (Br J Surg, 83: 647, 1996); Otera et al. (Eur Respir Rev, 19: 248-252, 2010); Antler et al. (Cancer, 49: 170-172, 1982); Fujiwara et al. (Gen Thorac Cardiovasc Surg, 59: 748-752, 2011); Stinchcombe et al. (J Clin Oncol, 24: 4939-4940, 2006); John et al. (J Postgrad Med, 48: 199-200, 2002); Carroll and Rajesh (Eur J Cardiothorac Surg, 19: 719-720, 2001); Brown et al. (Dis Colon Rectum, 23: 343-345, 1980). We report three cases of non-small cell (squamous cell) lung cancer with GI tract metastasis-two in the colon and one in the jejunum. Then we present a review of literature exploring various theories of metastasis, as an attempt to understand the reason of preferential tumor metastasis.