Anal Cancer

MD Anderson Cancer Center
Date: 08-10-09

 

Lisa Garvin: Welcome to Cancer Newsline, a weekly podcast series from the University of Texas, MD Anderson Cancer Center. Cancer Newsline helps you stay current with the news on cancer research, diagnosis, treatment and prevention, providing the latest information on reducing your family's cancer risk. I'm your host Lisa Garvin. Today we're talking with Cathy Eng MD She's an Associate Professor of Medicine in the Department of G.I. Medical Oncology at MD Anderson. Welcome Dr. Eng.

Dr. Cathy Eng: Thank you for having me here.

Lisa Garvin: Today our subject is anal cancer which has been very much in the news with the recent passing of Farrah Fawcett: kind of bringing recognition to the disease. But when we talk about diseases of the lower digestive tract, we tend to lump it into colorectal cancer but that's really several different types of cancer.

Dr. Cathy Eng: Anal carcinoma is a very distinct cancer from colorectal cancer and that majority of anal cancers are squamous cell cancers. And in actuality, it can be cured with chemotherapy combined with radiation therapy alone. It doesn't necessarily require surgery if you have the squamous cell subtype. So it's very different from rectal cancer which usually requires surgical resection.

Lisa Garvin: And anal cancer, that's what the last 5 or 6 inches of the colon? Or what section are we talking about?

Dr. Cathy Eng: It's the very lowest portion between the rectum and basically the anal margin: the lowest portion of your large intestine.

Lisa Garvin: As compared to colon cancer, anal cancer is fairly rare is it not?

Dr. Cathy Eng: It's about 5 thousand individuals per year are diagnosed with anal carcinoma.

Lisa Garvin: Are the symptoms the same? I mean do they develop polyps? Of course you're talking about squamous cells so probably not.

Dr. Cathy Eng: Right: no these don't develop from benign polyps like colorectal cancer. This usually is associated with other risk factors but not necessarily. It can just happen spontaneously but there's no standard screening for anal carcinoma. There are some tests that are being conducted in higher risk groups such as immuno-compromised patients as in HIV positive patients because they're at higher risk. So other risk factors are organ transplant patients, patients with a history of sexually transmitted diseases but the most commonly associated disease is the human papillomavirus, otherwise known as HPV which is actually the most common sexually transmitted disease in the world. Most women don't know they have it until they have an atypical pap smear. It's also associated - commonly associated - with individuals that have more than 10 sexual partners and also those that engage in anal intercourse. So HPV actually there's a hundred different subtypes of HPV but only 3 are more commonly associated with the development of cancer. And this is usually Subtype 16 which is also associated with cervical cancer. Although the research in cervical cancer is obviously a more common cancer, so it's something that there's a lot more funding to support. But the incidence of anal cancer continues to rise actually.

Lisa Garvin: Why do you think that is? Or are there studies underway to determine that?

Dr. Cathy Eng: I don't have a definitive reason to account for why the incidence continues to rise. I can tell you that when I first started seeing these patients, there was about 3500 cases per year and now we're up to about 5 thousand cases per year. Although that's not a huge amount, but the trend continues to increase. And as I stated before, a lot of individuals such as HIV positive patients are increased risk of developing HPV which also puts them at risk for developing anal carcinoma. So given that these patients are living longer, there may be some association with the development of this cancer. And prior studies have shown that even though individuals may be taking anti retro viral therapy for their HIV, it actually doesn't decrease the risk of anal carcinoma.

Lisa Garvin: In Farrah Fawcett's case she was metastatic...

Dr. Cathy Eng:  Right.

Lisa Garvin: ...and obviously succumbed to her disease. Is it asymptomatic in its earliest stages? Are there any symptoms that might point to anal cancer?

Dr. Cathy Eng: Well a lot of individuals think they have a hemorrhoid. That's their most common belief is that they have a hemorrhoid and they may develop some discomfort associated with prolonged sitting. They may develop some blood in their stool. They may just have some generalized, non-specific symptoms unless the mass is extremely large. And when the mass gets above 5 centimeters, it's actually a poorer prognosis for the patient. Those tend to be more aggressive and they don't tend to be as receptive to therapy.

Lisa Garvin: And are you catching people in early stages of anal cancer?

Dr. Cathy Eng: It just depends upon when they show up in all honesty. It depends upon how quick they are to refer themselves because a lot of people do think it's a hemorrhoid.

Lisa Garvin: And as for treatment, you said that surgery is generally not an option in this case?

Dr. Cathy Eng: Surgery's generally not needed in this case. So -- but that is only in squamous cell cancers of the anus which is a more common anal canal cancer. Chemo-radiation therapy is provided with the intent of cure and we only have the patient go on to surgery if they have residual disease or progression of disease. And in that case, because it involves the anal canal, they lose their sphincter and they end up with a permanent colostomy unfortunately.

Lisa Garvin: How many patients do have metastasis of their anal cancer?

Dr. Cathy Eng: So the majority of individuals present with early stage disease which can be cured, but about 15 to 20 percent of individuals do end up with metastatic disease as in the case of Farrah Fawcett. And because it's such a rare cancer with such a small percent of individuals that develop metastatic disease, there's no standard of care in actuality. There's no standard regimen utilized so it's commonly a regimen that may be used in more commonly presenting squamous cell cancers such as lung cancer and cervical cancer. At Anderson, we've actually recently conducted an analysis of our patients because I see a large number of these individuals. And we've noted that if they have good performance status - meaning they can go about their regular physical activities and tolerate treatment well despite having metastatic disease - the average patient was able to receive at least up to 3 different types of therapy and they prolonged their survival probably about -- the median is about 3 years. So they actually -- as long as their performance status is good and their lab tests are good, these patients were doing fairly well despite having no standard of care and despite having metastatic disease. If the patient only has 1 site of metastatic disease we try to refer them to a surgeon as we would for a colorectal cancer but that's not necessarily the majority of patients. The most common sites tend to be liver, lung and bones in my experience: bone involvement.

Lisa Garvin: Obviously when people think of the colon, you know they think of you know the colonoscopy and other you know screening tools, but it sounds like there really are no screening tools for anal cancer.

Dr. Cathy Eng: There aren't standard screening tools, no. In some studies they're doing almost like a pap smear of the anal canal very much like to test for cervical carcinoma but that's not standardized.

Lisa Garvin: So people who do engage in risky sexual practices, there's nothing they can go to their doctor and say, "Can you - you know - check me out?"

Dr. Cathy Eng: As with any other good physical examination, you should have a rectal examination. And so if there is something evident it should be noticed either by examination or palpation with a digital rectal examination.

Lisa Garvin: Dr. Eng, are there any upcoming studies or anything in the lab that might produce better screening or treatment of anal cancer?

Dr. Cathy Eng: So right now there are only 2 studies that are ongoing in the country. We actually had a third study which was just completed at our institution but that's a smaller Phase 2 study. We've had very good success and that will be out in publication shortly. That's using a more novel chemotherapy regimen. The 2 national trials that are ongoing does -- they're basically are the exact same trial, but one is specifically an HIV patient population so we -- I would definitely support such an effort because many individuals are being diagnosed that are HIV and a lot of times they were excluded from the original trials. So the trial that is ongoing is looking at the combination of 5-FU, Cisplatin and Cetuximab which is a chimeric or [inaudible] antibody against the epidermal growth factor receptor. Cetuximab is an antibody that's been evaluated in other squamous cell cancers such as lung cancer and head-neck cancer. And it's been found to be beneficial in that setting. So those are the 2 ongoing trials in the country. It's currently being amended but those are the only ones that are available right now. They recently completed a large study in the UK where they looked at whether or not you would benefit from -- Number 1, they looked at comparing 2 different regimens. One was 5-FU mytomycin which is considered by many to be the standard of care. Two, a regimen of 5-FU Cisplatin which is a regimen we commonly utilize here at our institution. And they found that they were equivalent across the board. They also looked at whether or not patients would benefit from additional therapy after completing their chemo-radiation to decrease their risk of occurrence. And thus far it doesn't look like there's any benefit to providing additional chemotherapy after the radiation's been completed. So I would say right now, we have basically 2 chemotherapy regimens that we can use off study that appear to be equivalent. There's no additional benefit for additional chemotherapy at the tail end of the chemo-radiation therapy. And whether or not there's any role for biologic therapies, we won't know until these other studies have been completed.

Lisa Garvin: But you say MD Anderson prefers the platinum based chemotherapy along with 5-FU?

Dr. Cathy Eng: That's the regimen we've commonly been utilizing in our group.

Lisa Garvin: Are there any final thoughts you'd like to tell us about, about anal cancer or prevention, screening and treatment?

Dr. Cathy Eng: I think it's just important, if you're having any symptoms such as bleeding or if you've had a hemorrhoid that you think is a hemorrhoid that's been there for a long time and it's causing discomfort, you should go to your physician. I think that this is a cancer that people tend not to want to discuss because it's a very private subject matter and a lot of people assimilate anal canal cancer specifically with a likely homosexual patient population and that's not necessarily the case. And I don't think that patient should be stigmatized just for this diagnosis. And definitely this is a very curable cancer if caught early if it's a squamous cell cancer. I should mention there's a such thing as anal adenocarcinoma which is not as common and that tends to be a bit more aggressive type of tumor. And it's treated very much like a rectal cancer. So that does require surgery.

Lisa Garvin: Okay, great. Thank you for being with us today.

Dr. Cathy Eng: Thank you.

Lisa Garvin: If you have questions about anything you've heard today on Cancer Newsline, contact Ask MD Anderson at 1-877-mda-6789 or online at www.mdanderson.org/ask. Thank you for listening to this episode of Cancer Newsline. Tune in next week for the next podcast in our series.