Gastrointestinal cancer-13-Anal,Pancreas
GASTROINTESTINAL CANCER PART-13
Welcome to the 13th part of educational series on GastroIntestinal Cancers. We learned in part 12 about treatment of rectal cancer, especially newer modalities which have led to improved outcome e.g. avoiding permanent colostomy. Also, how genetic testing has led to less side effects and more efficacy, and that most of such tests are available in India.
Question: Thank you Dr. Chiragbhai. What is the next sub site?
Answer: Next is Anal Cancer. This is a relatively rare cancer, which is divided into two: anal canal and anal margin(also known as perianal region). It is mostly squamous cell carcinoma.
It appears to be associated with HPV-16 infection, in majority of cases. This is similar to cancer of cervix, which is also associated with HPV infection. That is why immunosuppression, either in form of medicines or from HIV increases risk of anal cancer. This information becomes much more important now that we have a vaccine to prevent HPV infection.
Que: How does Anal cancer present?
Ans: Most patients present with bleeding per rectum, some with pain or mass. Most patients present in stage 1 or 2, as there is bleeding. However, one should not misinterpret this with piles. A careful examination is enough for diagnosis, to be confirmed by a biopsy. Staging work up includes CT scan of abdomen/pelvis and chest, or preferably PET-CT where available.
Patients should also undergo screening for cervical cancer with PAP smear, as there is known association, and a common risk factor i.e. HPV infection.
Que: How do you treat this disease?
Ans: In the past, surgery i.e. APR was the treatment. However, it is associated with permanent colostomy and a high failure rate i.e. about 50%.
Since early 80s, standard of care for anal cancer is chemoradiation, based on several randomized trials. All these studies showed that chemoradiation was better than surgery, with about 80% survival. Also, only a small number ultimately require colostomy, due to salvage surgery. Mitomycin and 5-FU is used with radiotherapy. Cisplatin appears to be of similar efficacy as mitomycin in phase 2 trials, but at least one randomized trial showed higher rate of colostomy with cisplatin compared with mitomycin.
Que: What about patients with HIV and Anal Cancer? Do they tolerate these treatments?
Ans: Good question. HIV infection incidence is high in India as well and is on a rapid rise. Therefore, we are all going to see HIV related diseases more and more commonly, including cancers. HIV infected patients have lower immunity, and use of chemotherapy is of concern. However, this has been studied, and patients with CD4 count over 200 can be safely treated with same regimen. Mitomycin is known to produce rare severe myelosuppression in otherwise healthy patients. One may use cisplatin in this group. They should be started on highly active antiretroviral therapy HAART to improve their immunity.
So, in summary, this is a comparatively rare cancer, frequently diagnosed early with careful examination, has very good rates of cure, good quality of life and better survival with use of chemoradiation rather than surgery, interesting association with HPV infection which may be of importance in era of vaccine, has rising rates due to rising HIV infection.
We will talk about hepatobiliary and pancreas cancers in upcoming parts of this series. Please feel free to send us your questions, at the email address noted.
Dr. Chirag A. Shah; M.D. Oncology/Hematology (USA), 98243 12144, 98988 31496
Diplomate American Board of Oncology and Hematology. Ahmedabad. drchiragashah@gmail.com
Shyam Hem-Onc Clinic. 402 Galaxy, Near Nehrunagar Circle, Ahmedabad.