Colorectal Cancer

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Cancer is when cells grow out of control. The cells form a clump of tissue called a growth or tumor. Cancer cells can invade nearby tissues. 然后它可以传播给其他人 parts of the body.

肿瘤可以是良性的也可以是恶性的. A benign tumor is not cancer and will not spread to 身体的其他部位. In the colon (large intestine), most benign growths are called polyps.

恶性肿瘤是癌症. Cancer cells invade and damage tissue around them. They can also enter the lymph and blood streams, spreading to 身体的其他部位. Colorectal cancer is the growth of malignant cells in the colon.

Cancer Cell Growth

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Normal Anatomy and the Development of Colorectal Cancer

The colon is the last part of the gastrointestinal tract. 这片土地上有食物 taken in and digested for the body to use. The colon's main job is to absorb water and salt from solid waste before it is passed from the body as stool (poop). The rectum is next. It stores stool until it is ready to be passed from the body through the anal canal.

Cell growth and death are normal processes in the body to replace old or damaged cells. The walls of the colon have cells that die and are replaced faster because of 消化过程. The colon may also be exposed to carcinogens, or things that can cause cancer. These carcinogens may come from waste expelled from the body, food 分解，和肠道细菌. They can cause damage to cells in the colon. This can lead to a high level of cell turnover. Places where there are rapid changes like this 是否更容易患癌症.

Polyps are another thing that can lead to cancer forming. 息肉是小的生长物 that can be found in the colon and rectum. 有几种类型. Most are benign, 但有些会变成癌症. The highest risk of cancer development comes from adenomatous polyps.

Cancer can happen anywhere in the colon, but it is most commonly found in the last section. Colorectal cancer may cause bleeding or make it hard for the colon to work as it should.

If the cancer grows beyond the colon or rectum, it can spread into nearby places, such as the urinary tract, reproductive organs, or anus. 它可以使它很难 these organs to work as well and cause issues such as problems passing urine.

It can also spread to lymph nodes or blood vessels, which can carry cancer cells to 身体的其他部位. The most common sites for colorectal cancer to spread to are lymph nodes in 身体的其他部位, the lungs, liver, or other organs in the 腹部和骨盆部位.

结直肠癌的种类

The wall of the large intestine is made of four layers. 从最里面到 outermost layer, they are named mucosa, submucosa, muscle, and serosa. Almost all 结直肠癌是 . That is, they start in the mucosa and 通过浆膜向外扩散. 其他类型包括:

• —these form from the hormone-producing cells of the intestinal tract
• -这些是由特殊细胞形成的 the colon wall, but can be found anywhere in the GI tract
• —these are rare and form from the muscular tissue of the intestine

Colon Cancer

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Rectal Cancer

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References

• Benson, A.P., Venook, A.B., et al. Colon Cancer. Version 2.2017 NCCN Clinical Practice Guidelines in Oncology. Journal of the National Comprehensive Cancer Network, 2017; 15 (3): 370-398.
• Colon cancer treatment option overview. National Cancer Institute website. Available at: http://www.cancer.gov/types/colorectal/patient/colon-treatment-pdq#section/%5F135.
• Colorectal cancer. 美国癌症协会网站. 可在:http://www.cancer.org/acs/groups/cid/documents/webcontent/003096-pdf.pdf.
• Colorectal cancer. EBSCO DynaMed网站. Available at: http://www.dynamed.com/condition/colorectal-cancer.
• Glynne-Jones, R., Wyrwicz, L., et al. Rectal cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 2017; 28 (suppl%5F4): iv22-iv40.