Background:
The literature about the causal relationship between lung cancer and tobacco smoking mostly concerns cigarettes. Hookah smoking is popular in the Kashmir valley, and is generally believed to be innocuous because of the passage of the smoke through water before inhalation. Hookah smoking is widely practiced in Kashmir and was found to be the commonest form of smoking amongst the patients with lung cancer. An earlier study from Kashmir also reported hookah smoking as the dominant form of smoking in a small cohort of 25 lung cancer patients.

Methods:
The study was conducted in the Sheri Kashmir Institute of Medical Sciences, Kashmir (India), a 650 bedded tertiary care university hospital that serves as the main referral center for the Pulmonary and Oncology cases of the Kashmir valley of the Indian subcontinent. Predesigned questionnaire in locally understandable language was tested and validated in a cohort of 10 cases of lung cancer and 20 controls and subsequently administered to the study cases and controls.

Results:
Study provides evidence that hookah smoking is associated with an increased risk of lung cancer in ethnic Kashmiri population with the risk being 6 times more as compared to non smokers. The study reaffirms the previous report by Nafae et al in the sixties who found hookah smoking as the commonest form of smoking in a cohort of 25 patients of lung cancer, seen in 20 of the 25, being exclusive in 17. Hookah smoking has since the olden times been the major form of smoking in Kashmir and is nearly the exclusive form of smoking in women (all of our female smokers had a history of hookah smoking).

Conclusions:
Hookah smoking in Kashmir is associated with increased risk of lung cancer and the commonly held belief that passage through water renders the smoke harmless seems ill founded and potentially dangerous. Further studies in this regard are warranted so as to fully analyze the various variables associated with the habit of hookah smoking and associated development of lung cancer.