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Treatment and stages of colorectal cancer

by | Jun 21, 2022 | Colorectal

Colorectal cancer develops along the inner lining of colon or rectum and is the most common cancer in Singapore. It is the top cancer for men, and second only to breast cancer for women. Singaporean Chinese males are at most risk as they have one of the highest age-standardised incidences of rectal cancer in the world.

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10 most common cancers affecting men & women (2014 – 2018)

Men

No. of cases

Women

No. of cases

Colon & rectum

6,129

Breast

11,232

Prostate

5,368

Colon & rectum

5,109

Lung

5,083

Lung

2,862

Liver

2,758

Corpus uteri (uterus)

2,769

Lymphoid neoplasms

2,358

Ovary & fallopian tube

1,897

Non-melanoma skin

1,975

Lymphoid neoplasms

1,809

Stomach

1,605

Non-melanoma skin

1,568

Kidney

1,494

Thyroid

1,483

Myeloid neoplasms

1,232

Stomach

1,160

Pancreas

1,119

Cervix uteri

1,088

(Source: Singapore Cancer Registry Annual Report 2018: Singapore Cancer Registry 50th Anniversary Monograph 1968-2017)

The most effective way to prevent colorectal cancer is through screening.

 

How colorectal cancer progresses


Colorectal cancer most commonly tends to arise from pre-existing polyps
(small growths along the lining of the colon). Polyps may be present in up to 25% of people aged 50, and they become more common with age.

While these polyps are largely asymptomatic, they can undergo genetic mutations over a period of five to 10 years, and become cancerous. Screening helps to pick up polyps so they can be removed before becoming cancer.

When cancer does develop, it starts in the innermost layer of the colon (the epithelium) before breaking out and spreading to the other layers of the bowel wall. The cancer cells can grow into blood and lymph vessels, and travel (a process known as metastasis) to other parts of the body.

Colorectal cancer starts in the epithelium and grows outwards.
Image: American Cancer Society

 

Stages of colorectal cancer


After a diagnosis has been made, doctors determine the best treatment options and calculate survival statistics by categorising the spread of cancer in stages. The higher the stage, the more serious the cancer. However, colorectal cancer is highly curable if caught early.

Stages:
Stage 0: The abnormal cells are confined to the epithelium.
Stage 1: The cancer has invaded through the epithelium into the bowel wall.
Stage 2: Cancer has penetrated the outer layer of the colon or rectum.
Stage 3: The cancer has spread to surrounding lymph nodes.
Stage 4: The cancer has metastasised to other organs such as the liver or lungs.

Surgery is the first line of treatment for colorectal cancer. In the earliest stages, surgery alone can offer high cure rates. The cancer is removed with the surrounding lymph nodes and sent for further examination to confirm the stage of the disease. In most cases, the intestines can be reconnected and normal bowel function is restored.

Other treatment options include radiation therapy which uses X-rays to kill cancer cells. Radiation is often used for treatment of rectal cancer and can be given prior to surgery to shrink a tumour, or after surgery to reduce the risk of local recurrence.

Chemotherapy involves taking drugs that are ingested by mouth or injected into the bloodstream to destroy tumour cells that have spread to other parts of the body. They hinder the growth of cancer but can have unpleasant side effects. Nevertheless, chemotherapy helps patients with incurable cancer to live longer.

Other treatments for advanced cancer include:

  1. Targeted therapy – using drugs that suppress cancer cells by modulating growth factors.
  2. Immunotherapy, which stimulates or enhances the body’s immune system to fight and destroy cancer cells.

 

 

This article has been fact-checked by Dr Denis Cheong, colorectal surgery specialist of Surgi-TEN Specialists at Farrer Park Hospital.

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