Second primary cancers after anogenital, skin, oral, esophageal and rectal cancers: etiological links?

The Swedish Family-Cancer Database was used to analyze second cancers after oral, esophageal, rectal, cervical, genital and skin (squamous cell carcinoma) cancers. A strong and consistent association of second cancers was observed at all these sites, in men and women. As a novel finding, an association of rectal cancer with the human papillomavirus (HVP)-related cancers was shown. New evidence on an excess of skin cancer with the HPV-related cancers was also provided. As an epidemiological study, the associations were strong and often supported by a number of comparisons. These could not be explained by bias or long-term treatment related effects. However, whether the findings on rectal and skin cancer are due to HPV or other infections, transient or inherited depressed immune function or other constitutional factors remains to be established.