Characteristics of included studies
| Participants | |||
|---|---|---|---|
| Study | Cases | Controls | Exposure |
| Lung cancer | |||
| Gupta et al31 | 265 histologically confirmed patients with lung cancer from Chandigarh in India | 525 age-matched and sex-matched hospital visitors | Waterpipe smokers used mixture of crude tobacco and jaggery, coarse and undefined sugar on the head of waterpipe compared with being exposed to <1 cigarette per day for <1 year |
| Koul et al32 | 251 histologically confirmed patients with lung cancer from Kashmir Valley in India | 500 age-matched healthy individuals selected generally from relatives of patients | Waterpipe smokers used processed tobacco mixed with molasses, compared with non-smokers |
| Aoun et al33 | 50 histologically confirmed patients with lung cancer from Lebanon | 100 hospital visitors | Former waterpipe smokers (type of tobacco was not mentioned) compare with non-former waterpipe smokers |
| Oesophageal cancer | |||
| Khan et al34* | 100 histologically confirmed oesophageal cancer cases from northern India | 100 healthy individuals from the same area as cases | Waterpipe smokers in comparison with non-smokers, but the type of tobacco was not defined |
| Malik et al35* | 135 histopathologically confirmed cases with oesophageal cancer from the Kashmir Valley | 195 age-matched and gender-matched individuals who visited hospital | Waterpipe smokers in comparison with non-smokers, but the type of tobacco was not defined |
| Nasrollahzadeh et al36 | 300 histopathologically confirmed cases with ESCC† from north of Iran | 571 hospital-based participants matched to the case for neighbourhood of residence, age and sex | Waterpipe smokers in comparison with non-smokers, but the type of tobacco was not defined |
| Dar et al37* | 702 histopathologically confirmed cases with ESCC from Kashmir, India | 1663 hospital-based participants individually matched to the cases for sex and age | Waterpipe smokers divided based on intensity and duration of smoking, cumulative use and frequency of changing water were compared with non-smokers |
| Shakeri et al38 | 30 histologically confirmed cases with ESCC from Iran | 260 age-matched and sex-matched controls from two series, one hospital-based and the other population-based | |
| Head and neck cancer | |||
| Feng et al39 | 636 histologically confirmed cases of nasopharyngeal cancer from Algeria, Morocco and Tunisia | 615 healthy individuals matched with cases by centre, age, sex and childhood household type (urban/rural) | Participants were categorised as never or ever waterpipe smokers |
| Khlifi et al40 | 169 histologically confirmed head and neck cancer cases from Tunisia | 351 hospital-based cancer-free participants | Waterpipe smokers are those who smoked once per day, and for more than 1 year, compared with non-smokers |
| Other types of cancer | |||
| Bedwani et al41 | 151 men with incident histologically confirmed invasive bladder cancer from Egypt | 157 hospital-based cancer-free men | Participants were categorised as never or ever smoked tobacco; ever smokers divided into former and current smokers |
| Shakeri et al42 | 309 histologically confirmed cases of gastric cancer from Iran | 613 population-based participants matched to the cases for age, sex and neighbourhood | Subjects were divided into never and ever smoking waterpipe; ever users were defined as those reporting consuming the product at least once a week for minimum of 6 months |
| Hosseini et al43 | 137 men with histologically confirmed prostate cancer from Iran | 137 healthy men selected from the same neighbourhood as cases, and matched for age | Pipe or watepipe smoking were considered and participants divided in ever smoking or non-smoking |
*It seems there is overlap between 3 Indian studies, since cases were recruited from the same hospital during the same time frame.
†ESCC, Oesophageal squamous cell carcinoma.