It may feel a little awkward to talk about anal cancer.
“It’s an area of the body that people don't talk about too often,” says Cullen Taniguchi, M.D., Ph.D., a radiation oncologist specializing in anal cancer and other gastrointestinal cancers. “Many times, people who get it won't even declare that they have it.”
Another obstacle? When it is talked about, anal cancer is often mistaken for or grouped together with colorectal cancer instead of being recognized as a distinct cancer type.
But talking about anal cancer is important, both for educational purposes and allowing those affected by anal cancer to feel less alone – especially with growing rates of HPV-related anal cancer. And while the topic may be uncomfortable, it isn’t devoid of hope.
“This is something we see all the time,” says Taniguchi. “This is something we can cure.”
Now, Taniguchi is continuing the conversation by answering questions on anal cancer topics ranging from prevention to treatment.
What is anal cancer, and how is it different from colorectal cancer?
Colorectal cancer occurs along the gastrointestinal tract, a long tube that helps you digest your food and remove waste. Anal cancer is a cancer at the very end of that tract: the anus and the sphincter muscles that help control your anus.
A pathologist will call colorectal cancer an adenocarcinoma, which is a cancer of the glands. But anal cancer tends to be squamous cell carcinoma, which is usually on the surface of the anus. Even though it's connected to the rectum and the colon, anal cancer looks different under a microscope, and it is treated differently, as well.
Who is at risk for anal cancer?
Anal cancer is uncommon. There are only a few thousand people who get it in any given year across the United States. The strongest risk factor is HPV exposure. Almost anyone who's ever had sexual activity has been exposed to HPV; you don't need to have had anal sex. Any kind of sexual activity is enough exposure to be at risk.
So many people get exposed to HPV. It’s fairly common, and in most cases, your immune system clears it, so it goes away on its own. But sometimes it doesn’t and can progress to cancer. The rate of HPV-related anal cancer is increasing, although the reason for this increase is unknown. The hope is that rates will go down significantly in many years as more people get HPV vaccinations.
We think that when HPV leads to anal cancer, it’s related to changes in your immune system. It tends to come about when your immune system is a little weaker. I usually tell patients it's bad luck. We really don't know why they get anal cancer when 99% of people exposed to HPV don't.
How is anal cancer diagnosed? Do people mistake anal cancer symptoms for other things?
This happens all the time, because a rare cancer of the anal canal is not something that is on people's mind. Because symptoms are sometimes anal bleeding, it can feel like a hemorrhoid. Many times, people don’t realize something is wrong until it gets really big, or there’s pain. Many times, it shows up on a colonoscopy. Someone doing an examination notices a lump and they’ll biopsy it, and it turns out to be cancer.
Because the symptoms are so common, we don’t want people thinking they have anal cancer when it's something more common. But the bottom line is if you have any concerns, make sure you have a doctor take a look at it. If you think it's a hemorrhoid, odds are that it's probably a hemorrhoid. But if it's bothering you for more than a week or two, you should probably get checked out.
What does anal cancer look like? Is it always a lump that you can see?
A lot of times there's no lump at all. It’s actually on the inside, and it can’t be felt without a medical examination. When it's coming out on the outside, people tend to notice it, and it gets taken care of a little quicker. Anal cancer looks like a piece of flesh, but it feels harder than a hemorrhoid. A hemorrhoid feels like a scar, kind of soft. If it’s cancer, it tends to feel hard like a pebble or frozen pea.
What happens at an initial appointment for someone with anal cancer symptoms?
A doctor will do a full history to understand how long your symptoms have been going on, then do a physical examination that usually involves a rectal exam. If there's anything in the anal canal that is abnormal, like lumps or bumps, that would trigger a referral to a specialist who could use a camera and biopsy to determine whether it's cancer.
What treatments are available for anal cancer?
Radiation therapy is the main form of treatment for anal cancer in stages I through III, which is when the disease is just in the pelvis and anal canal.
We use Intensity Modulated Radiation Therapy (IMRT). It’s a way that we can give radiation but bend the beams to where we need them using advanced computing power.
The first and hopefully only treatment is radiation, usually with some chemotherapy. You get a little bit of chemotherapy with the radiation to make the radiation work better. It's not a full dose of chemotherapy that will make your hair fall out and make you terribly sick; it's a lower dose. You go through that for five or six weeks.
Surgery is available as the backup option if radiation doesn’t work. We save surgery for if radiation doesn't work – if the cancer grows back – because once you do surgery, you need a permanent ostomy bag.
What lifestyle changes can a patient expect following anal cancer treatment?
Near the end of radiation treatment, and probably for the first few months after treatment, the anal area will be sensitive. It's like getting a sunburn. It’s uncomfortable; it will take some time to heal.
One of the major problems from treatment is not the treatment itself; it’s that the cancer has grown and maybe damaged the muscle in the sphincter that controls when you poop. Your body will have to relearn how to use that muscle because the cancer has damaged it.
Some patients have very few things to recover from and can bounce back quickly. Some take up to a year to fully recover. Many patients can continue working and doing most of their daily activities except for maybe a couple of weeks near the end of treatment.
What are the latest research advances for anal cancer?
We are also looking at whether we can reduce the dose of radiation in some early-stage anal cancer cases. We try to match the dose to the stage. There's a thought that maybe we're still giving too much radiation for these early-stage cancers when the cure rate is more than 95%. We're trying to reduce the dose of radiation to reduce long-term side effects.
In advanced anal cancer, immunotherapy is sometimes used. We think that some anal cancer comes on because the immune system is weakened, so making the immune system stronger and more active with immunotherapy can make a lot of sense.
One of the things my lab is interested in is how the gut microbiome affects anal cancer. The bacteria in our gut control the way we metabolize food and how cancers respond to treatment. We think it makes a lot of sense that the same bacteria are mixed in with the tumor in the anal canal. We are studying how patients’ gut bacteria change during radiation. We've found that there are some kinds of bacteria that might be able to predict whether a patient would have more toxicity and whether a patient might have a better response to treatment.
What advice would you give to somebody recently diagnosed with anal cancer?
Get your treatment at a place that treats this disease a lot. Most places will see this kind of cancer once a year at most, but at MD Anderson, we see two to five anal cancer patients every week, so this is not rare for us. If you can’t come to MD Anderson, make sure that you go someplace that has a National Cancer Institute-designated cancer center.
Don't be afraid to seek out a second opinion if you need to, because your best shot at being cured is your first time through treatment. If the cancer comes back, it's much, much harder to treat. Make sure you get the best advice and go with a team that you trust right from the start, and that will increase your chances of successful treatment.