Rectum

Grade 1: low grade, cells well-differentiated. Grade 2: moderate grade, cells moderately differentiated. Grade 3: high grade, cells undifferentiated. There is also a classification of that the grade can't be assessed.¹¹ || || Patients are likely to become very tired during radiation therapy, especially in the later weeks of treatment.¹³ ||
 * Epidemiology: || Incidence is equal among men and women. ¹ ||
 * Etiology: || Enviornmental factors and dietary factors are assumed to be the cause for colorectal cancer. Diets high in animal fats and meats and also low intake of fiber and calcium also have a clear association with colorectal cancer. 2 ||
 * Signs & Symptoms: || Presenting symptoms include hematochezia, change in bowel habit, nausea, vomiting, anemia, or abdominal mass. ³ ||
 * Diagnostic Procedures: || Digital rectal examination, endoscopy, H&P, palpatation for extrarectal mass, and examination of liver, supraclavicular if the mass is near the dentate line. Women should get a complete pelvic exam involving a rectovaginal exam. ⁴ ||
 * Histology: || Most common histology is adenocarcinoma consisting of 90-95% of cases. The rest of the histology types include mucinous adenocarcinoma, signet-ring cell carcinoma, and squamous cell carcinoma. ⁵ ||
 * Lymph Node Drainage: || Lymph node drainage starts at the superior rectal vessels and continues until it empties into the inferior mesenteric nodes. The middle, lower and middle rectal vessels terminate into the internal iliac nodes. Sometimes these nodes connect via efferent lymph nodes into the anal lymph nodes. ⁵ ||
 * Metastatic Spread: || Risk of metastatic disease correlates with the depth of bowel wall invasion by the tumor and it occurs in 10-20% of tumors confined to the wall.⁶ Low-grade tumors have a 30% chance of metastatic spread through lymph nodes and high-grade tumors have an 80% chance of spread through the lymph nodes to distant sites.⁷ Metastatic disease can also be spread through the blood stream with the main distant site being the liver.⁸ 30% of rectum cancer patients that have had definitive surgery experience metastatic disease and the most common sites are: liver, lung and peritoneum.⁹In metastatic nodal disease, the disease can "skip" to other sites without continually disseminating. "Skip" metastases are thought to be caused by blockages in the lymph system.¹⁰ ||
 * Grading: || General grading system recommended by the American Joint Committee on Cancer and the International Union Against Cancer is based on the degree of cell differentiation:
 * Staging: || According to Chao, et. al. there are 4 possible staging systems for colon cancer: Dukes, Astler-Coller, Modified Astler-Coller and the American Joint Committee on Cancer TNM system. Chao, et. al. advise that the first 3 staging systems can only be used postoperatively and the TNM system can be used either before or after surgery.¹²:
 * Radiation Side Effects: || The side effects of radiation therapy depend mainly on the amount of radiation given and the part of the body that is treated. Side effects of rectal cancer radiation therapy to the abdomen and pelvis may include nausea, vomiting, diarrhea, bloody stools, rectal leakage, or urinary discomfort. In addition, the skin in the treated area may become red, dry, and tender.
 * Prognosis: || The corresponding 5-year relative rectal survival rates were:

· 90.4 percent for localized · 68.1 percent for regional · 9.8 percent for distant · 34.6 percent for unstaged. The 5-year relative rectal cancer survival rates by race and sex were:

· 66.0 percent for white men · 64.2 percent for white women · 55.6 percent for black men ·<span style="font-family: 'Times New Roman'; font-size-adjust: none; font-size: 7pt; font-stretch: normal; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal;"> <span style="color: #ff00ff; font-family: 'Verdana','sans-serif'; font-size: 10pt;">53.9 percent for black wo <span style="color: #ff00ff; font-family: Verdana,Geneva,sans-serif; font-size: 10pt;">men.¹³ || <span style="color: #ff00ff; font-family: 'Arial','sans-serif'; font-size: 10pt;">Depending on the stage of your cancer, 2 or more types of treatment may be used at the same time, or used one after the other. Surgical resection is the treatment of choice. Shrinking fields should be used with initial irradiation fields designed to treat the primary tumor volume and regional lymph nodes. Smaller fields can be used to treat the primary tumor bed to higher doses as clinically indicated. The width of PA portals should cover the pelvic inlet with a 2cm margin; the superior margin is usually 1.5cm above the level of the sacral promontory. In patients who have had anterior resection, the usual inferior margin is below the obturator foramina. If the pelvis is treated, lateral fields should be used for a portion of the treatment to avoid as much small bowel as possible. Bladder distention and prone position hrinking field technique are useful techniques for displacing the small bowel out of the pelvis. The posterior field margin for lateral fields is critical because the rectum and perirectal tissues lie just anterior to the sacrum and coccyx; the posterior field margin should be at least 1.5 to 2.0 cm behind the anterior bony sacral margin. The entire sacral canal should be included for locally advanced disease to avoid sacral recurrence form tumor spread along nerve roots included in the initial irradiation volume treated to 45 GY. External iliac nodes are not a primary lymph node drainage site and are not included unless pelvic organs wit external iliac drainage (prostate, upper vagina, bladder, uterus) are involved by direct extension. Temporary acute and moderate to moderately severe perinea discomfort can be mitigated with use of three field technique (PA, and lateral s with wedges on latera l fields) ¹³ || Small bowel 50 Gy, xx, 40 Gy Colon 55 Gy, xx, 45 Gy Rectum 75 Gy, 65 Gy, 60 Gy¹⁴ || Figure 1: IMRT Rectum with DRR from Eclipse¹⁵
 * Treatments: || <span style="color: #ff00ff; font-family: 'Arial','sans-serif'; font-size: 10pt;">The 4 main types of treatment for colorectal cancer are:
 * <span style="color: #ff00ff; font-family: 'Arial','sans-serif'; font-size: 10pt;">surgery
 * <span style="color: #ff00ff; font-family: 'Arial','sans-serif'; font-size: 10pt;">radiation therapy
 * <span style="color: #ff00ff; font-family: 'Arial','sans-serif'; font-size: 10pt;">chemotherapy (often called just "chemo")
 * <span style="color: #ff00ff; font-family: 'Arial','sans-serif'; font-size: 10pt;">targeted therapies (called monoclonal antibodies)
 * TD5/5: || <span style="color: #008000; display: block; font-family: TimesNewRomanPSMT,serif; font-size: 13pt; text-align: left;">Organ (1/3), (2/3), (3/3)

Figure 2: four-field, and three-field beam arrangements¹⁶

References 1. Philip Rubin, //Clinical Oncology-A Multidisciplinary Approach for Physicians and Students.// 7th edition, Philadelphia, PA: W. B. Saunders Co.; 1993. 2. Nishele Lenards, [|www.uwlax/edu], D2L - Clinical Oncology for Medical Dosimetrist: Colon and Rectum, accessed 1/19/2010 3. Chao KS, Perez CA., Brady LW. //Radiation Oncology - Management Decisions//. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002. 4. Chao KS, Perez CA., Brady LW. //Radiation Oncology - Management Decisions//. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002. 5. Washington CM, Leaver D. //Principles and Practice of Radiation Therapy//. 2nd ed. St. Louis, MO: Mosby. 2004 6.Gunderson LL, Haddock MG, Goldberg, R, et. al. Alimentary Cancer. In: Rubin P, ed. //Clinical Oncology: A Multidisciplinary Approach// //for Physicians and Students//. 8th ed.Philadelphia, PA: W.B. Saunders Company; 2001:724. 7.Gunderson LL, Haddock MG, Goldberg, R, et. al. Alimentary Cancer. In: Rubin P, ed. //Clinical Oncology: A Multidisciplinary Approach// //for Physicians and Students//. 8th ed.Philadelphia, PA: W.B. Saunders Company; 2001:724. 8.Gunderson LL, Haddock MG, Goldberg, R, et. al. Alimentary Cancer. In: Rubin P, ed. //Clinical Oncology: A Multidisciplinary Approach// //for Physicians and Students//. 8th ed.Philadelphia, PA: W.B. Saunders Company; 2001:725. 9. Chao KS, Perez CA., Brady LW. //Radiation Oncology - Management Decisions//. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002:399. 10. Chao KS, Perez CA., Brady LW. //Radiation Oncology - Management Decisions//. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002:396. 11. Spitalnik PF, di Sant'agnese PA. The Pathology of cancer. In: Rubin P, ed. //Clinical Oncology: A Multidisciplinary Approach// //for Physicians and Students//. 8th ed.Philadelphia, PA: W.B. Saunders Company; 2001:54. 12. Chao KS, Perez CA., Brady LW. //Radiation Oncology - Management Decisions//. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002:398. 13. Chao KS, Perez CA, Brady LW. Radiation Oncology- Management Decisions. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002 14. Chao KS, Perez CA., Brady LW. // Radiation Oncology - Management Decisions //. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins. 2002. 15. United Hospital. Eclipse planning system. Accessed January 21, 2010. 16. Washington CM, Leaver D. // Principles and Practice of Radiation Therapy //. 2nd ed. St. Louis, MO: Mosby. 2004