Stool in the blood, diarrhea, constipation and abdominal cramps, are some of the common symptoms of sigmoid colon cancer.
As we all know, the large intestine, a 1.5 m long tubular structure, is mainly involved in the elimination of solid waste matter. The large intestine consists of three major sections: cecum, colon and the rectum. The sigmoid (around 16 inches long) is a part of the colon that is situated between the descending colon and the rectum (the last 8 inches of the large intestine). When we talk about colon cancer, it usually occurs in the sigmoid or the rectal area.
Causes
In any type of cancer, healthy cells tend to multiply indiscriminately. So what are the factors that may trigger excessive growth of cells in the colon? Doctors believe that people suffering from chronic intestinal disorders like Crohn’s disease and ulcerative colitis are in the risk zone of sigmoid colon cancer. Following a diet that is high in fatty foods as well as leading an inactive lifestyle can also increase the risk of malignant tumor growth in the colon.
Stages
The colon is made up of 4 tissue layers. The innermost layer of the colon is the mucosa and the outermost layer is referred to as the serosa. Depending upon which layer is affected with the tumor, the sigmoid colon is categorized into following stages:
- Stage 0: This is the primary stage in which the tumor is very small and has only affected the innermost mucosa layer.
- Stage 1: If the detection of cancerous growth reveals that the tumor cells are confined to mucosa layer and the overlying muscle tissue layer then the cancer is said to be in stage 1.
- Stage 2: In case, the diagnosed tumor has reached the outer serosa layer, it is a cause for concern. This is because, there is a high probability that the cancer has penetrated into nearby tissues of the colon.
- Stage 3: The cancerous cells have penetrated the lymph nodes located near the colon and will soon spread to other organs of the body.
Symptoms
After knowing what causes colon cancer, let’s discuss its symptoms. Presence of cancerous growth in the sigmoid colon does not mean that the symptoms will appear immediately. A small tumor in the sigmoid rarely shows any symptoms. However, as the tumor size increases over time, the person starts experiencing uncomfortable changes in bowel function. This is the reason why it is difficult to detect cancer in its initial stages of development. Symptoms that appear when the tumor size is large enough to disrupt bowel function are discussed below:
Firstly, the stool color changes. It appears dark or one may see a portion of the stool is bright red in color. This indicates that the tumor is bleeding during bowel evacuation. As a result, the blood combines with the fecal matter leading to change in stool color. As the cancer advances, healthy bowel movement may soon become a thing of the past. The patient may either suffer from persistent diarrhea (frequent bowel movement) or constipation, which means the tumor size has become large enough to obstruct bowel movement. The cancer may also cause gas, bloating and abdominal pain. A significantly large tumor can further aggravate the pre-existing symptoms and in addition to that cause unexplained weight loss, fatigue and vomiting.
Treatment
When diagnosed early, treatment involves removing the part of the colon (sigmoid) through surgery. If the tumor has invaded the serosa layer as well as lymph nodes, then besides undergoing surgery, the patient is put on chemotherapy drugs to kill the cancer cells that have spread beyond the sigmoid. Chemotherapy for colon cancer involves intake of oral drugs that are formulated to destroy cancer cells. The lymph nodes that are an integral part of the immune system, are circular structures found near the colon and in the armpits. Their main function is to produce white blood cells to combat infections. This is stage 3 and as the tumor has spread to the surrounding tissues of the sigmoid, surgery alone won’t work to stop cancerous growth.
Prognosis
Prognosis of any disease tells how it will progress and its impact on the patient. It gives an idea about survival chances of sigmoid cancer patients after or during the course of treatment. The prognosis in this case, completely depends on when the cancer is detected and how far it has spread. Prognosis of sigmoid colon cancer is often expressed in terms of ‘5 year survival rate’. This parameter is expressed in percentage and indicates the number of patients that may live for minimum period of 5 years, after the tumor is diagnosed. For instance, if 5 year survival rate of a blood cancer is 25%, it denotes that out of 100 patients confirmed with tumor growth, only ¼ of them would survive for minimum 5 years. On the whole, colon cancer survival rates are dependent how far the cancer has penetrated.
In case of sigmoid colon cancer, the 5 year survival rate can increase or decrease depending upon when the tumor is diagnosed. Early diagnosis and treatment is the key to increase the lifespan of the patient. The cancer diagnosed in the later stages reduces the 5 year survival rate drastically. Also, if the cancer is diagnosed in the early stages and subsequently removed, and in case it doesn’t return within a span of 5 years, then it indicates that the patient has recovered completely.
