Table 1.

Characteristics of eligible studies

Author, yearNo. cases/controlsSelection of controlsPro allele frequency in cases/controls (%)Genotyping methodSource of DNA for casesControl group in HWE
Olschwang, 199171/115Independent individuals from the CEPH31/35PCR-RFLPBloodYes
Kawajiri, 199384/347Unrelated individuals randomly selected from a pool of 2,500 healthy individuals from a prospective cohort38/35AS-PCRBloodYes
Sjalander, 1995155/206Placental samples from deliveries at the Umea University hospital; UC controls were excluded33/29PCR-RFLPBloodYes
Murata, 1996115/152Patients with noncancerous pulmonary disease from the outpatient of the same hospital where cases were sampled36/40AS-PCRBloodYes
Wang, 199961/140Healthy individuals ages ≥65 y43/44PCR-RFLPCancer tissueYes
Sayhan, 200167/76Healthy volunteers with no evidence of cancer or gastrointestinal disease39/44PCR-RFLPCancer tissueYes
Hamajima, 2002147/241Noncancer patients who underwent gastroscopy at the same hospital from which the cases were sampled36/40PCR-CTPPBloodYes
Gemignani, 2004352/316Patients admitted to departments of the same hospital from which cases were sampled24/21primer extensionBloodYes
Schneider-Stock, 200476/85Healthy individuals30/31Melting curveBloodYes
Kruger, 2005126/245Healthy blood donors21/23PCR-RFLPBloodYes
Sotamaa, 2005186/32399 adult individuals representing a weighted sample of the Finish population and 224 male blood donors from the same geographic region as the patients23/27PCR-SSCPBloodYes
Koushik, 2006442/904For women: cancer-free participants from the NHS; for men: cancer-free participants from the PHS27/26TaqManBloodYes
Perez, 200653/109Healthy individuals23/35AS-PCRCancer tissueYes
Perfumo, 200660/188Patients with a negative colonoscopy, hospital controls, and blood donors28/20PCR-RFLPBloodYes
Webb, 20062,558/2,694Healthy individuals recruited among spouses or unrelated friends of the patients with malignancies25/26Illumina Bead ArraysBloodYes
Tan, 2007467/563Randomly selected from population registers19/22SequencingBloodYes
Zhu, 2007345/670Cancer-free individuals randomly selected from a cancer screening program50/40PCR-RFLPBloodYes
Csejtei, 2008102/97Healthy individuals from archived data20/21AS-PCRCancer tissueYes
Dakouras, 200893/95Healthy individuals33/45AS-PCRCancer tissueNo
Grünhage, 200896/220Individuals in whom colonoscopy did not reveal abnormal mucosal growth. Those with personal/family history of cancer were excluded.25/26PCR-RFLPBloodYes
Mammano, 200890/643Two control groups were used: 321 healthy individuals and 322 centenarians31/35PCR-RFLPBloodYes [per study report]
Cao, 2009156/293Healthy individuals44/37PCR-RFLPNormal mucosal cellsYes
Polakova, 2009612/612Individuals undergoing colonoscopic investigation28/27PCR-RFLPBloodYes

NOTE: Percentages have been rounded to the nearest integer. Further details are provided in Supplementary Table S1.

Abbreviations: AS, allele-specific; CEPH, Centre d'Etude du Polymorphisme Humain (Human Polymorphism Study Center); CTPP, confronting two-pair primers; HWE, Hardy-Weinberg equilibrium; NHS, Nurses Health Study; PHS, Physicians' Health Study; QC, quality control. HWE was tested in the control groups using an exact test (34). SSCP, single-strand conformation polymorphism; UC, ulcerative colitis.