Retroperitoneum

There are various reasons to the causes, effects, and patterns seen with retroperitoneal cancers. Etiology Retroperitoneal tumors are rare and can be benign or malignant in nature. As its name implies, they grow in the retroperitoneal space and outside of the organs located in this space. There are a variety of neoplasms affecting individuals such as:
 * **Epidemiolgy:** || Spencer
 * Patients usually present with complaints of abdominal pain or having a mass in 60-70% of the cases seen. 1
 * 50% of patients usually see some kind of weight loss or loss of appetite at time of diagnosis. 1
 * Most patients with this kind of tumor don’t seek medical treatment due to the tumors being very asymptomatic. 1
 * There are many different kinds of retroperitoneal tumors associated with paraneoplastic syndromes. 1
 * Adults – Usually see Mesenchymal Neoplasms 2
 * Lipoma or Liposarcoma
 * Children – Usually see Rhabdomyosarcoma and Lymphoma. 2
 * The majority develops germ cell tumors ||
 * **Etiology:** || Pablo
 * Leiomyosarcoma
 * Fibrosarcoma
 * Rhabdomyosarcoma
 * Retroperitoneal adenocarcinoma
 * Liposarcoma
 * Malignant fibrous histiocytoma
 * Extra-gonodal germ cell tumor
 * Malignant peripheral nerve sheath tumors

The exact cause of retroperitoneal tumors is still being investigated. Certain disorders of the kidneys have been associated with these neoplasms, these include kidney stones and nephrotic syndrome. Diseases of organs such as the pancreas, adrenal glands and colon are also associated with retroperitoneal tumors. 3 || Patients tend not to seek medical attention due to being asymptomatic until tumors become large. In 60% to 80% of cases, the patients usually present with abdominal pain. Weight loss and loss of appetite are some other symptoms that may be present when the patient seeks medical attention. Depending on the type of retroperitoneal tumor other symptoms may include: paraneoplastic syndrome, intermittent hypoglycemia, or excessive catecholamine. 4 || The histology of the tumor tends to play a big part when determining the mode of invasion of retroperitoneal tumors. 6 If the tumor behavior is one of expanding, it is most likely a benign soft tissue tumor or a well-differentiated sarcoma (myxoid liposarcoma). 6 If there is involvement with the aorta and the vena cava, the chances are good that the histology will be a high-grade sarcoma, a germ cell neoplasm, or a lymphoma. 6 If the vertebral foramina is invaded in a dumbbell shaped pattern and the cells are small and round, then the histology is most likely neuroblastoma or. 6 Also, when discussing tumors of the retripertioneum, there is an incidence of 60% that adjacent organ involvement will occur. 6 || || Retroperitoneal sarcomas have a high rate of local recurrence and disseminated disease throughout the abdomen. Approximately 80% of recurrences occur within 5 years. Pulmonary metastases and hepatic metastases are common. A study showed that patients diagnosed with pulmonary mets have a median survival of 6-12 months, whereas if surgery is done the survival can increase. With hepatic mets, median survival is 30 months for patients who have hepatic resection, compared to 11 months for those who did not. Many other primary cancers can spread via the retroperitoneal lymph nodes, and often these lymph nodes contain metastasis. 8 || <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">When dealing with the retroperitoneam, the grade is a sign of how likely the cancer will spread. <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif; vertical-align: super;">9 <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;"> There are a few different factors associated with the grading system and how exactly soft tissue sarcomas (retroperitomeum) is graded. <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Grade <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif; vertical-align: super;">9 <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">GX – The grade of the tumor cannot be assessed because of incomplete information <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Grade 1 (G1) – Total score of 2 or 3 <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Grade 2 (G2) – Total score of 4 or 5 <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Grade 3 (G3) – Total score of 6 or higher || Staging of retroperitoneal tumors is based on histology. Depending on the location of the tumor side effects from radiation treatments may include: The main prognostic factors for retroperitoneal tumors are the histology, invasiveness, and resectability. These tumors are considered resectable if there is no involvement of the aorta, vena cava, iliac, superior mesenteric vessels, spinal cord, nerve plexus, or peritoneal seeding. Additionally, tumors are not considered resectable if there is metastasis. Of patients that get a full excision of the tumor, 45% have a 5-year survival rate. For those that only receive a partial excision, that number drops dramatically to 8%. 5 || Pre-op radiation therapy helps decrease the risk of tumor seeding. Pre-op irradiation is the preferable method although intraoperative irradiation and postoperative irradiation with a boost may be performed. A radiograph can be used to delineate tumor volume and it will be outlined by the air filled bowel. When designing treatments, the liver, small bowel, stomach and the kidneys are the structures that should be avoided. The kidneys are the primary limiting structure. One kidney can be completely included in the field, while the other can only receive a maximum for 18Gy. The liver shouldn’t receive more than 30Gy. Typically the field arrangement will use AP/PA with lateral fields being used sparsely. A 3-5 cm margin should be added to the gross tumor and pre-op dose should be taken to 45Gy. Surgery can follow radiation by 4 weeks. If a boost is still required, then 15Gy can be given either with external beam, interstitial implant, or intraoperatively using an electron beam. The total dose to the retroperitoneum is limited to 50Gy due to the stomach and small intestine involvement. 12 || <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">2. Lenards, N. Peritoneum. [PowerPoint]. La Crosse, WI: UW-L Medical Dosimetry Program; 2013. 3. Radiopaedia.org. Web site. []. Accessed Jun 10, 2013. 4. Chao KSC, Perez CA, Brady LW. Soft tissue sarcoma. In: Chao KSC, Perez CA, Brady LW, eds. //Radiation Oncology Management Decisions//. Philadelphia, PA: Lippincott, Williams and Wilkins; 2011: 703-717. 5. Chao KS, Perez CA, Brady LW. Radiation Oncology Management Decisions. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011. 6. Chao KS, Perez CA, Brady LW. Radiation Oncology Management Decisions. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2002:567 7. Eggener S, Carver B, Sharp D, et al. Incidence of Disease Outside Modified Retroperitoneal Lymph Node Dissection Templates in Clinical Stage I or IIA Nonseminomatous Germ Cell Testicular Cancer. The Journal or Urology. 2007;177(3):937-943. 8. Windham TC, Pisters PWT. Retroperitoneal Sarcomas. Cancer Control. 2005;12(1);41. []. Accessed June 14, 2013. 9. Soft Tissue Sarcoma Staging/Grading. American Cancer Society Web Site. http://www.cancer.org/cancer/sarcoma-adultsofttissuecancer/detailedguide/sarcoma-adult-soft-tissue-cancer-staging. Accessed June 11, 2013. 10. Chao KS, Perez CA, Brady LW. Radiation Oncology Management Decisions. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2002: 567-573. 11. Radiation treatments. Pleural Mesothelioma Web Site. [] Accessed June 11, 2013. 12. Lenards, N. Retroperitoneum. [PowerPoint]. La Crosse, WI: UW-L Medical Dosimetry Program; 2013. <span style="color: #800080; font-family: Arial,Helvetica,sans-serif; font-size: 12px;">13. Vann A, Dasher B, Chestnut S, Wiggers N. Portal Design in Radiation Therapy. 2nd ed. Columbia, SC: The R.L. Bryan Company; 2006:131. || Back to Week 3
 * **Signs & Symptoms:** || Becky
 * **Diagnostic Procedures:** || Adam
 * Complete blood cell count and blood studies to establish baselines for bone marrow, hepatic, and renal status
 * CT scans to determine tumor size and extent
 * MRI can be superior to CT for being able to differentiate tumor from muscle 5 ||
 * **Histology:** || Megan
 * **Lymph node drainage:** || Kevin Tsai 7
 * **Metastatic spread:** || Erin
 * **Grading:** || <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Spencer
 * <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Differentiation – These are given a score of 1-3, with 1 being a form of cancer that looks similar to normal cells and 3 being a form a cancer that looks very abnormal. <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif; vertical-align: super;">9
 * <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Mitotic Count – This is a measure of how many cancer cells are seen when under the microscope. Scored 1-3, with the lower score meaning fewer cells dividing. <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif; vertical-align: super;">9
 * <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">Tumor Necrosis – This is a measure of how much of the tumor is made up of dying tissue. Scored from 0-2, where a lower score means there is less dying tissue present. <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif; vertical-align: super;">9
 * **Staging:** || Pablo
 * Mesenchymal origin: skeletal muscle, peripheral nerve, fat, fibrous tissue, vessels
 * Extra-gonadal germ cell
 * Primary retroperitoneal adenocarcinoma 10 ||
 * **Radiation side effects:** || Becky
 * Skin damage—red or dry in the affected area
 * Fatigue—may be due to anemia
 * Mouth problems—dry mouth or taste bud damage
 * Diarrhea
 * Nausea and Vomiting
 * Urinary or bladder changes 11 ||
 * **Prognosis:** || Adam
 * **Treatments:** || Megan
 * **TD 5/5:** || Kevin Tsai
 * Small Bowel - 45 Gy - Obstruction/Perforation 13
 * Colon - 45 Gy - Obstruction/Perforation
 * Stomach - 55 Gy - Ulceration/Perforation
 * Liver - 30 Gy - Liver Failure
 * Kidney - 23 Gy - Nephritis
 * Spinal Cord - 47 Gy - Myelitis/Necrosis ||
 * **References:** || <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif;">1. Chao, K, Perez, C, Brady, L. Radiation Oncology Management Decisions. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2002. 703-710.