Rectal Cancer

Rectum is the lower most portion of the large bowel and is about 10 to 15 cm long. It joins the anus below and act as a temporary storage for feces before they are expelled.

Cancer of the rectum and the colon have various similarities and commonly referred to as Colo-Rectal Cancer (CRC). CRC is the third most common cancer in men and second in women world wide (approx. 10% of total cancers).Rectum is situated in a tight space in the pelvis and is in close proximity to the urinary bladder, seminal vesicles and prostate in males and uterus and vagina in females. This results in involvement of these structures once the tumor spreads beyond the rectum. Additional treatment may be required to down stage the disease for a curative intent and to save the anal sphincters which controls the voluntary act of defecation. Recent advances in the understanding of the rectal cancers and introduction and adaptation of neo-adjuvant therapy has resulted in improved survival after rectal cancer.

Common symptoms of the rectal cancer are:

• A recent change in the bowel habit such as diarrhea, constipation or frequency of stools passage
• Blood in stools of passage of dark colored stools
• Passing narrow stools with mucus
• Painful defecation with passage of blood during defecation
• Feeling that the bowel has not emptied completely
• Pain in the abdomen
• Iron deficiency anemia
• Weakness
• Unexplained and unintended weight loss
• Fatigue

Causes of the rectal cancer:

Aberrations in the normal rectal cells where changes occur in the DNA and results in the uncontrolled and disorderly growth of the cells results in formation of the rectal cancer. With time the cancer cells divide and invade the surrounding structures resulting in the spread of the tumor.
Genetic mutations that results in increased risk of rectal cancers are-

• Hereditary nonpolyposis colorectal cancer (HNPCC)
• Familial adenomatous polyposis (FAP)

Risk factors for Rectal cancer:

• Age: age >50 years increases the risk of development of rectal cancer
• Personal or family history of colorectal cancer or polyps
• Inflammatory bowel disease
• Inherited syndromes- HNPCC, FAP
• Dietary factors- consumption of diet low in vegetables and fibers and high red meat consumption.
• Sedentary life style
• Diabetes
• Obesity
• Smoking
• Alcohol consumption
• History of previous radiation therapy

Screening for the colorectal cancer:

Usually start by the age of 50 years but more frequent or early screening may be recommended if one or more risk factors are present. Screening is usually done by colonoscopy.

Diagnosis of rectal cancer:

• Routine Lab Tests
• Colonoscopy
• Carcinoembryonic Antigen (CEA)
• Computed Tomography (CT) scan
• MRI for Staging
• PET Scan- whole body to rule out metastasis

Rectal cancer stages:

Rectal cancers fall into one of five possible stages (stage 0 through stage 4). The stages, in simplified form, are:

• Stage 0. Cancer cells on the surface of the rectal lining (mucosa), sometimes within a polyp
• Stage I. Tumor extending below the rectal mucosa, sometimes penetrating into the rectal wall
• Stage II. Tumor extending into or through the rectal wall, sometimes reaching and growing on or sticking to tissues next to the rectum
• Stage III. Tumor invading lymph nodes next to the rectum, as well as structures and tissues outside the rectal wall
• Stage IV. Tumor spread to a distant organ or lymph nodes distant from the rectum

Staging also involves examining a sample of tissue taken from the tumor (a biopsy) to determine the tumor's grade. Low-grade tumors tend to grow and spread slowly. In contrast, high-grade tumors grow and spread quickly, so they may need more-aggressive treatment.

Treatment:

Treatment of rectal cancer is usually multimodal where one or more modality are used in combination or in sequence which helps in the improved survival of the patient.
Options available are-

• Surgery
• Chemotherapy
• Radiation therapy

Surgical options offered to the patient depends upon following factors:

• The stage and grade of the cancer
• The location of the tumor in the rectum
• The size of the tumor
• Age
• General health
• Medical history

Commonly performed surgeries are:

• Laparoscopic/ Robotic Abdomino-perineal resection with end colostomy
• Laparoscopic/ Robotic Low anterior resection
• More extensive surgery depending on the stage and spread of the tumor

Chemotherapy and Radiation therapy - are used in either before the surgery (Neo-adjuvant) or after the surgery and biopsy report (Adjuvant) depending on the stage/ evaluation of the disease.