WHAT IS IT
The anus is the opening that connects the terminal part of the intestine with the outside. The food ingested through the whole digestive system and waste are turned into stool, after a stop in the rectum (the last part of the large intestine), through the anal canal and are expelled through the anus.
The anal canal, a tube approximately 4 cm long, is coated in its inner part by a mucous membrane formed by different types of cells that can be transformed into cancer cells. In addition to the anal canal also the anal opening real or the glands connected to the anal canal (that produce mucus in order to facilitate the passage of stool) may give rise to a tumor.
INCIDENCE
The anal cancer is rare. The annual incidence (number of new cases in a year) is about 1-3 new cases per 100,000 people and, in general, women are more affected than men.
WHO IS AT RISK
One of the main risk factors for cancer of the anus is the Human Papilloma virus (HPV), also responsible for other cancers, particularly cervical.
Not all strains of HPV are carcinogenic, in many cases, in fact, the body’s immune defenses are enough to clear the infection. However, some strains (especially 16 and 18) are carcinogenic and increase the risk of developing cancer. The virus is spread mainly through sexual contact with infected partners, and condom use does not protect against infection (although reduced) since for contracting the infection is sufficient contact between two infected areas.
Infection with HPV is not the only risk factor for anal cancer: have a greater risk of getting sick even smokers, people with a high number of sexual partners over a lifetime, those with immune system particularly weak (after organ transplant or because of HIV) and those with previous diagnosis of other cancers (cervix, vulva, vagina, penis) usually related to the HPV virus.
TYPES
Not all cancers affecting the anus give rise to a cancer: among the benign forms can remember the polyps that occur at the level of the anal canal mucosa or warts that generally occur just outside the anal opening or the lower part of the anal canal and which are also caused by the human Papilloma virus (HPV). Among the forms of cancer that affect this region, guests may remember:
– Squamous cell carcinomas, which represent the majority of anal cancers;
– Adenocarcinomas, which develop at the top of the anus, near the rectum or in the anal canal and glands are treated as rectal cancer;
– Basal cell carcinomas, which are more rare and develop from epithelial cells that surround the anal opening. Generally they are considered skin tumors;
– Melanomas, which relate to the anus cells that produce melanin and are very rare.
As with other cancers (cervix, vagina), also for anal cancer pre-cancerous conditions exist: it comes from changes in the cells called dysplasias that may be potential tumors and which must therefore be kept under control. They speak in these cases of anal intraepithelial neoplasia (AIN, anal intraepithelial neoplasia) and anal squamous intraepithelial lesion (SIL, squamous intraepithelial lesion).
SYMPTOMS
In some cases the anal cancer is entirely asymptomatic for a long period and the first symptom is rectal bleeding. The bleeding is usually minor and are sometimes accompanied by itching and / or pain in the anal region, change in diameter of stool, abnormal leakage from the anus and swollen lymph nodes at the level of anal and inguinal region.
These symptoms are not necessarily related to a tumor: also for hemorrhoids or anal fissures, for example, the symptoms are the same. Contact your doctor is the only way to dispel any doubts.
PREVENTION
One of the strategies to prevent anal cancer is to avoid HPV infections and HIV. In this sense it is useful to try to limit the number of sexual partners, use condoms for anal intercourse (which still does not guarantee complete protection from infection, since it may be sufficient simply contact) or avoid relationships with infected partners, too if, in fact, HPV infection can remain completely asymptomatic and difficult to identify. Against infection with HPV vaccines are available that are effective in preventing infection by some strains of the virus (6, 11, 16 and 18) and which currently are administered systematically only to women (in Italy is recommended vaccination girls around the age of 12).
Since the link between HPV and certain male cancers, such as those of the anus and penis becomes increasingly clear, several scientific societies are considering whether to recommend vaccination also to men. The United States has approved the use of one of the two available vaccines for the prevention of cancer and anal warts in both men and women.
Finally we must not forget that say stop the cigarette reduces the risk of developing anal cancer.
DIAGNOSIS
The discovery of an anal cancer sometimes occurs at random: it happens that the doctor notices that there is something wrong during a visit with rectal examination performed for other reasons or, perhaps, in the course of an operation to remove hemorrhoids.
In the event of suspected cancer, further tests before we can formulate efficient diagnosis you are needed. It starts usually with an endoscopy, which involves introducing a thin probe through the anus which allows you to see the inside of the anal canal (anoscopy) or with a probe a little ‘longer, also the rectum and part of the colon (proctosigmoidoscopy).
If tests show the presence of suspicious regions we proceed with the biopsy, or the removal of a piece of fabric which is then analyzed under the microscope. In the case of very small tumors that have not yet invaded the inner mucosal layer, it is possible to proceed with the complete removal of the diseased tissue already during the examination. The biopsy can also be used to see if the cancer has already spread beyond the anus: in this case it picks up a piece of fabric from any enlarged lymph nodes or from sentinel nodes (the first that the tumor encounters in its diffusion path over the organ of origin).
Additional imaging tests (CT, PET, MRI, x-ray and ultrasound) are typically used to understand in detail the spread of the disease.
EVOLUTION
To assign a stage (that is, to define how far the disease has spread) tumors that affect the anus using the TNM system created by the American Joint Committee on Cancer (AJCC). With this system we take into account the extent of disease (T), the involvement of lymph nodes (N) and the presence of metastasis (M).
THERAPY
The choice of the treatment of anal cancer depends on many factors such as the stadium, the location and the type of illness or general health condition of the patient.
In many cases it is possible to proceed with surgery if the tumor is small and has not spread, surgery is limited to the removal of the region involved and a small portion of surrounding tissue, while in the more advanced cases of the disease intervention it is generally more extensive and, in some cases, provides for the total removal of the rectum and anus. It then becomes necessary the subsequent creation of an artificial anus in the abdomen (colostomy) to allow the escape of stool which will be collected in an outer bag.
Radiation therapy is another treatment option for anal cancer and can be either external (with a radius that goes to hit precisely the region affected by cancer and often also the surrounding lymph nodes) and internal (called brachytherapy, with small “seeds” radioactive positioned directly at the tumor level).
Chemotherapy is also used to treat anal cancer. The various chemotherapeutic drugs can be administered alone or in combination as the main therapy or as adjuvant therapy after surgery, to eliminate cells that have not been removed with the bisturi.Infine is possible to use a combination of chemotherapy and radiotherapy, as it was found that some drugs may enhance the effectiveness of radiation.[/vc_column_text][/vc_column][/vc_row]