Anal canal cancer

Introduction to anal canal cancer Anal canal cancer refers to cancers below the dentate line to the anus opening, which is rare in rectal cancer. More often than the elderly, men are slightly more than women. Anal canal cancer includes cancer of the skin around the anal canal and anus, and the incidence rate is about 3% of rectal cancer. basic knowledge The proportion of illness: 0.0055%--0.0082% Susceptible people: more common in older men Mode of infection: non-infectious Complications: fecal incontinence, hematuria, bladder spasm

Anal canal cancer

(1) Causes of the disease

The true cause of anal canal cancer is not yet clear, but studies have shown that it is caused by multiple genes out of control under multiple factors. In the past, long-term chronic stimuli such as anal fistula, genital warts and immune diseases (such as Crohn's disease) were associated with anal canal cancer. In recent years, it has been found that human papillomavirus (HPV) is closely related to it, especially HPV-16, 50% to 80% of anal canal cancer cells have HPV-16, and abnormal sexual behavior is also a risk factor for anal canal cancer. 47% of homosexual patients have a history of anal canal sputum, the risk of anal canal cancer is 12.4 times that of normal spouses, 30% of female patients have anal history, and immunosuppression, such as postoperative renal transplantation, has an incidence of anal canal cancer. The normal population is 100 times higher, and there is abnormal gene expression in anal canal cancer. 67% of anal canal cancers have p53 gene mutations, 71% of anal canal cancers have the expression of oncogene C-myc, and the distribution is abnormal. In addition, some people pay attention to it. To smoking is also an important cause of anal canal cancer. The incidence of male and female smoking is 9.4 times and 7.7 times higher than that of normal people.

(two) pathogenesis

1. Pathology Anal canal is the junction of internal and ectoderm, so the histological source of tumor is more complicated, and it can be roughly divided into three categories: epithelial cell tumors (such as squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, etc.), non- Epithelial cell tumors (such as sarcoma, lymphoma, etc.) and malignant melanoma.

Anorectal cancer is the most common squamous cell carcinoma, accounting for more than 2/3, according to the degree of cell differentiation, moderate and poorly differentiated cancer, a small number of adenocarcinoma, as sarcoma and lymphoma are rare in the anal canal, malignant melanoma Less than 1% of anorectal tumors, of the 574 cases of anorectal tumors in the Cancer Hospital of Sun Yat-sen University of Medical Sciences, only 4 cases of melanoma, accounting for 0.7%, but their malignancy is extremely high, rapid growth, rapid transfer to regional lymph nodes And other organs, the prognosis is very poor.

The spread of anal canal cancer is mainly lymphatic metastasis, and mainly transfers to the para-rectal lymph nodes along the superior rectal artery, merges into the upper rectal lymph nodes, and then transfers to the sub-inferior mesenteric artery. The anal canal cancer can also metastasize to the lateral lymph nodes. As for the iliac crest, the total lymph node is transferred downwards mainly through the perineum and the subcutaneous tissue of the inner thigh to the inguinal superficial lymph node. A few of the posterior lateral hips enter the inguinal shallow lymph node and then merge to the deep inguinal lymph nodes. And sputum, common lymph nodes, visible, inguinal lymph node metastasis can often become the first station lymph node metastasis, and rectal cancer is different, and second, anal canal cancer local invasion can invade the anal sphincter, vaginal posterior wall, perineum, prostate and bladder , causing anal fistula vaginal fistula or anal canal bladder spasm, so in the treatment of anal canal cancer with abdominal perineal resection combined with rectal resection, the scope of perineal resection should be more extensive than that of rectal cancer surgery. The third route of anal canal cancer is the menstrual bloodway. To the liver, lungs, bones, peritoneum and so on.

2. The clinical pathological staging of staged anal canal cancer is more and more complicated. It is currently the most widely used in the TNM classification (1997) of the International Union Against Cancer (UICC).

Staging criteria:

T primary tumor

Tx primary tumor failed to determine

T0 has no primary tumor

Tis carcinoma in situ

T1 tumor maximum diameter 2cm

T2 tumor maximum diameter > 2cm

T3 tumor maximum diameter > 5cm

T4 tumors, regardless of size, have invaded adjacent organs such as the vagina, urethra, and bladder (only invading the sphincter does not belong to T4)

N regional lymph node

Nx regional lymph nodes failed to determine

N0 no regional lymph node metastasis

N1 rectal lymph node metastasis

N2 unilateral intraorbital and/or inguinal lymph node metastasis

N3 lymph node and inguinal lymph node metastasis, and/or bilateral intraorbital and/or bilateral inguinal lymph node metastasis

M distant transfer

Mx distant transfer failed to determine

M0 has no distant transfer

M1 has a distant transfer.

Anal canal cancer prevention

1, reasonable adjustment of diet structure: diet should be diversified, avoid high-fat, high-protein, low-cellulose recipes, eat less irritating food, keep the stool smooth, prevent constipation.

2. Carry out censuses and strive to achieve early detection and early treatment.

3, the diagnosis of similar diseases should be clearly diagnosed and actively treated to avoid misdiagnosis and missed diagnosis.

Anal canal cancer complications Complications, incontinence, hematuria, bladder spasm

There are many invasive symptoms in the development of anal canal cancer. For example, when lymph node metastasis and involvement of obturator nerves, intractable perineal pain can occur and radiate to the inner thigh; tumor invasion of sphincter can cause fecal incontinence; invasion of vagina into anal canal - vaginal fistula, stool discharge from the vagina; abnormal urine or hematuria or urinary closure when invading the prostate; can cause anal canal - bladder spasm when invading the bladder; if hepatic metastasis has occurred, liver metastasis, lung metastasis, gastric metastasis, etc. may occur Symptoms and signs.

Anal canal cancer symptoms Common symptoms Anal pain Fecal pus and blood inguinal lymph nodes swollen incontinence Anal itching Defecation not feeling the anal area redness and painful lumps in anxious after anal canal polyps

The early symptoms of anal canal cancer are not obvious. The clinical manifestations of advanced stage are similar to the lower rectal cancer. The main aspects are as follows:

1. Stool habits change the number of defecations, often accompanied by urgency or heavy bowel movements.

2. Fecal trait changes The faeces become thin or deformed, often with mucus or pus.

3. Anal pain Anal pain is the main feature of anal canal cancer. At first, anal discomfort is gradually aggravated, resulting in persistent pain, which is more obvious afterwards.

4. Anal itching with secretions due to anal canal cancer secretions stimulate the perianal skin, the patient anal itching, secretions with odor.

5. Anal canal lump digital rectal examination or anal speculum examination can be seen in the anal canal ulcer or polypoid, sputum mass, there are infiltrative mass with anal canal narrowing.

6. Inguinal lymphadenopathy Anal canal cancer patients often have a side or bilateral inguinal lymph nodes, multiple, pliable, or with pain.

Anal canal cancer examination

Histopathological examination, anal canal cancer is mostly squamous cell carcinoma, a small number of adenocarcinoma or malignant melanoma.

1. The anus can be touched near the tooth line, and the finger is stained with odor.

2. Anal speculum examination showed that the mass in the anal canal was polypoid, scorpion-like or ulcerated and infiltrated, and the anal canal was narrowed.

Diagnosis and diagnosis of anal canal cancer

According to medical history, clinical manifestations, diagnosis is mainly based on histopathology and anal speculum examination results.

Differential diagnosis

The clinical manifestations of anal canal cancer are easily confused with anal fistula, polyps, anal fissure, perianal abscess, sexually transmitted disease granuloma, anal canal skin tuberculosis, and perianal skin cancer.

1. Rectal cancer in the lower rectal cancer is also bloody stools, frequent changes in bowel habits, urgency and heavy complaints, some tumors can invade the dentate line, making it difficult to distinguish between rectal cancer or anal canal cancer, but only noticed rectal cancer Anal pain is less common or tough, and the central location of the tumor can be determined on the tooth line or under the finger or rectum. In addition, most of the biopsy rectal cancers are adenocarcinomas, and rectal adenocarcinomas have less inguinal lymph node metastases. Lymphatic occlusion is retrograde to the inguinal lymph nodes, and the prognosis of rectal adenocarcinoma is better than anal canal cancer.

2. Anal fistula is more common in clinical practice. Generally, it begins with anal abscess. Local pain is obvious. After abscess is formed, the pain is also reduced. The anal fistula is mostly in the middle of the anal canal and is connected with the dentate line. The mucous membrane is intact, sometimes forming an induration or a cord-like shape. When the finger is examined, it can be seen that the purulent discharge from the fistula is discharged, and the symptoms are often improved after sitting in the bath and anti-infection. The anal fistula can be confirmed by probe examination, if it is suspected of cancer, A biopsy should be used to confirm the diagnosis.

3. Perianal skin cancer Anal skin cancer often accompanied by anal discomfort, obvious itching, small masses on the anal margin and gradually increase, slow growth, less pain, odorous secretion after ulcer formation, edge valgus eversion, biopsy For better differentiated squamous cell carcinoma, the keratinization is more, the malignancy is low, the metastasis is not easy to occur, and the radiotherapy effect is good. As long as the observation is careful, the center point of the tumor is below the anal margin, although the ulcer has occurred, the inguinal lymph node There are not many transfers.

4. Malignant melanoma The tumor is rare in the anal canal. The typical melanin looks like a thrombotic sputum, but it is palpated as a hard nodule, occasionally tender, with pigment and ulcer on the surface. The diagnosis is not difficult. It is worth noting that half Melanoma can be misdiagnosed without pigmentation, and biopsy can confirm the diagnosis.

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