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New Treatments for Anal Cancer

Tumors of the anus and rectum are uncommon because these are tumors really of the anal canal. I am going to talk about the squamous, the basaloid, cloacogenic tumors of the anus. Basically anal canal tumors fall into this squamous, basaloid or cloacogenic category. Above the pectinate line there is a zone of transition here from an adenomatous epithelium of the rectum and the large bowel, down to a non-keratinizing squamous epithelium of the anal canal. Then out here in the perianal skin you have typical skin cancers, which would be keratinizing squamous carcinomas. There is a big difference, biologically, in the treatment orientation between a tumor that occurs

If you look at the epidemiology of anal cancer you’ll see that it represents a relatively small percentage of the large bowel cancers. Of course, the anus is only about an inch, inch-and-a-quarter, long. If you look, there has been a difference in the occurrence of this tumor. For most of this century it was more common in people above the age of 55, it was

Just to try and sort out the pathology, we have the uncommon tumors which we are not really going to talk about, and then we have the anal cancers. They essentially are squamous cell cancers, or derived from squamous cell cancers. The anal skin cancers are keratinizing just like

It appears that there is a strong association with human papilloma virus in anal cancers. There are several factors that are important here; genital warts are strongly associated with the risk of anal cancer and if you look at anal cancers, a large percentage of them are positive for the

How might human papilloma virus be associated with the development of a neoplasm? Well, this is really very interesting and again it tells us something about viral carcinogenesis. The human papilloma virus gets incorporated into the genome and produces a couple of proteins; one from

If you look at the etiology and how people might get anal cancer, certainly in males there is a very strong correlation with anal receptive intercourse. There doesn’t appear to be the correlation in females. This is from Cancer Medicine, Brenda Shank in 1994. There also is a strong correlation with HPV virus. Presumably the HPV virus is transmitted in male homosexual populations as a sexually transmitted disease. If you look at other associations, just like cervical cancer, there is a mild association with herpes virus type II. Immunosuppression is actually

These are very interesting, very recent, data suggesting or giving you an insight in to what may be happening with concomitant HIV infection, or for that matter immunosuppression, and the presence of patients who have a history of anal cancers. This was presented at the Digestive Diseases Week a couple of months ago in Florida from a group in Paris. Essentially what they did is they took patients who were HIV positive and HIV negative, all of them had anal condylomata. Because genital warts are not terribly uncommon and people can get them without being immunosuppressed. They treated the genital warts as you would, resected them, froze

What about treatment and prognosis with anal cancer? There are a couple of things that are important. One is the size of the tumor and another is the differentiation of the tumor and obviously the metastatic dissemination of the tumor, if it has disseminated. Although the vast majority of the times, anal cancers - because of their location -are picked up fairly early. The

What about the results? The standard therapy for anal cancer, before 20 years ago -18-20 years ago - was abdominoperineal resection. Obviously abdominoperineal resection is something that can’t be taken too lightly since you are removing the whole anorectal mechanism and you leave a patient with a permanent colostomy. In a review of some 460 patients this was

Looking at radiation therapy alone in the treatment of patients with anal cancer, and you get a local control rate of somewhere from 60-70% and a five year survival rate of somewhere around 50-65%. So radiation alone has some benefit. Now the radiation therapists are in a sense like chemotherapists in that if a little radiation is good someone is always going to say, "Well, a lot of radiation is better." These are data from France from Papillion, and what he did

Well, when the modern era arrived where data, using the combination of mitomycin, 5-FU and radiation in patients with basaloid and squamous cancers of the anus. The original work was done at Wayne State University by Dr. Nigro and his colleagues. Many people picked up on it and initially the combination of 5-FU, mitomycin and radiation was used in patients with larger