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What Is The Pathogenesis Of Colorectal Cancer

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Posted on Tue, 7 Apr 2015
Question: 1 Describe the pathogenesis of colorectal cancer from the initial cellular mutation to the
diagnosis of stage IIA colorectal cancer.
2 Describe two (2) modifiable and three (3) non-modifiable risk factors for colorectal cancer and explain how these risk factors may have contributed to the development of colorectal cancer.
doctor
Answered by Dr. Indu Kumar (4 hours later)
Brief Answer:
It typically starts as a polyp which may become cancerous over time.

Detailed Answer:
Hello

Colorectal cancer is the development of cancer in the colon or rectum.
It typically starts as a polyp(benign tumour) which may become cancerous over time.Polyps may become dysplastic and development into cancer is a muti-step process involving the inactivation of a variety of tumour-suppressor and DNA repair genes along with simultaneous activation of oncogenes(that causes cancer).
Single germline mutation in the adenomatous polyposis coli (APC) tumour suppressor gene is responsible for the dominantly inherited syndrome familial adenomatous polyposis.Clinical expression of the disease is seen when the inherited mutation of one APC allele is followed by a second hit mutation or deletion of the second allele.

Colorectal cancer is the abnormal growth of cells that has ability to invade or spread to other parts.
Tumors in the right colon are usually polypoid or fungating exophytic masses where as tumors involving left colon are more commonly annular or encircling in nature that may produce an "apple-core" appearance.

There are many risk factors for colorectal cancer like age,life style,genetic and family history,smoking,alcohol etc.
Inflammatory bowel disease also increase the risk of colorectal cancer.

Diet,smoking,alcohol etc are modifiable factors whereas age,genetic and family factors are non-modifiable risk factors.

Stage 0 is in the earliest stage and this stage is also known as carcinoma in situ.
Stage I indicate cancer has grown through the muscularis mucosa into the submucosa (T1).It has not spread to nearby lymph nodes or distant sites.

Stage IIA indicate cancer has grown into the outermost layers of the colon or rectum but has not gone through them.It has not reached nearby organs.It has not yet spread to the nearby lymph nodes or distant sites.

Hope I have answered your query.
Further queries are most welcome.

Take Care
Dr.Indu XXXXXXX
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Indu Kumar (21 hours later)
1 Describe the sequence of events that occurs in the pathogenesis of colorectal cancer from the initial cellular mutation to the diagnosis of stage IIA colorectal cancer.
2 explains how age and gentic factors may have contributed to the development of colorectal cancer.

Describe the action and mechanism of action of metronidazole (Flagyl) and Morphine in relation to its administration to Colorectal cancer patient
doctor
Answered by Dr. Indu Kumar (17 hours later)
Brief Answer:
Colorectal cancer development is a multistage process.

Detailed Answer:
Hello

Colorectal cancer development is a multistage process that results from progressive accumulation of genetic mutations.
However,epigenetic alterations of the chromatin,particularly the chromatin components in the promoter regions of tumor suppressors and oncogenes also play key roles in colorectal pathogenesis.Epigenetic regulation is done primarily by DNA methylation and selective histone modifications in cancer cells.
Chromosomal instability leads to aneuploidy and losses at the molecular level of portions of chromosome 5q,chromosome 18q,chromosome 17p and mutation of the KRAS oncogene.Important genes involved in these chromosome losses are APC (5q),DCC/MADH2/MADH4 (18q) and TP53.
These changes lead to increased mucin production by tumour cells.
It then starts growing with time.With advancement of age,chances of gene defect increases.

Morphine is primarily used as analgesia for cancer patients and metronidazole can be used as antibiotic if patient has underwent any intervention.

Hope I have answered your query.
Further queries are most welcome.

Take Care
Dr.Indu XXXXXXX
Note: For further queries related to kidney problems Click here.

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
Answered by
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Dr. Indu Kumar

Radiologist

Practicing since :2004

Answered : 6729 Questions

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What Is The Pathogenesis Of Colorectal Cancer

Brief Answer: It typically starts as a polyp which may become cancerous over time. Detailed Answer: Hello Colorectal cancer is the development of cancer in the colon or rectum. It typically starts as a polyp(benign tumour) which may become cancerous over time.Polyps may become dysplastic and development into cancer is a muti-step process involving the inactivation of a variety of tumour-suppressor and DNA repair genes along with simultaneous activation of oncogenes(that causes cancer). Single germline mutation in the adenomatous polyposis coli (APC) tumour suppressor gene is responsible for the dominantly inherited syndrome familial adenomatous polyposis.Clinical expression of the disease is seen when the inherited mutation of one APC allele is followed by a second hit mutation or deletion of the second allele. Colorectal cancer is the abnormal growth of cells that has ability to invade or spread to other parts. Tumors in the right colon are usually polypoid or fungating exophytic masses where as tumors involving left colon are more commonly annular or encircling in nature that may produce an "apple-core" appearance. There are many risk factors for colorectal cancer like age,life style,genetic and family history,smoking,alcohol etc. Inflammatory bowel disease also increase the risk of colorectal cancer. Diet,smoking,alcohol etc are modifiable factors whereas age,genetic and family factors are non-modifiable risk factors. Stage 0 is in the earliest stage and this stage is also known as carcinoma in situ. Stage I indicate cancer has grown through the muscularis mucosa into the submucosa (T1).It has not spread to nearby lymph nodes or distant sites. Stage IIA indicate cancer has grown into the outermost layers of the colon or rectum but has not gone through them.It has not reached nearby organs.It has not yet spread to the nearby lymph nodes or distant sites. Hope I have answered your query. Further queries are most welcome. Take Care Dr.Indu XXXXXXX