Retroperitoneal Sarcoma (RS)

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Retroperitoneal Sarcoma (RS)

• Hashmi

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• approximately 15 of all sarcomas
• approximately 33 to 55 of all retroperitoneal
  tumors
• malignant tumors arising from mesenchymal cells
• located in adipose, muscle, connective tissue, or
  soft tissue
• contrast to carcinomas
• epithelial origin (breast, colon, pancreas, etc)
• metastasize via hematogenous route
• typically to the liver or lung
• most common variants of RS
• liposarcoma (40)
• leiomyosarcoma (30)
• malignant fibrous histiocytoma (lt10)

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• most common clinical presentation is an abdominal
  mass
• non-specific, vague abdominal discomfort or pain,
  weight loss, and early satiety, intestinal
  obstruction or bleeding, lower extremity swelling
  or pain
• computed tomography (CT) is the initial test of
  choice, then MRI
• tumor location and size
• relationship to surrounding anatomic structures
• identification of metastatic lesions
• differential diagnosis
• germ cell tumor, teratoma, cyst, hematoma and
  abscess, functioning and non-functioning adrenal
  tumor, renal tumor, pancreatic tumor, advanced
  gastrointestinal carcinoma, soft tissue sarcoma,
  lymphoma, and other neoplasms

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• surgery is the standard treatment
• surgical failures
• large tumor size on presentation
• inability to achieve wide surgical margins
• limitations of existing adjuvant radiation and
  chemotherapy regimens
• failure can be seen even 5 to 10 years in nearly
  90 of patients
• long-term recurrence rate is thought to be over
  70
• prognosis is worse for RS than for other trunk or
  extremity sarcomas
• gt30 incidence of vascular involvement
• gt60 of cases of these lesions require
  multi-visceral resections
• colon, kidney, small bowel, pancreas, bladder

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• Low grade sarcomas
• treated surgically
• adjuvant radiation therapy or chemotherapy
• High grade sarcomas
• neoadjuvant chemotherapy
• these tumors are more likely to undergo
  metastasis
• tumors are treated more aggressively

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• neo-adjuvant chemotherapy may be used in an
  attempt to shrink the tumor
• postoperative radiotherapy may be of benefit
• adjuvant chemotherapy surgical therapy may
  produce a modest improvement in the
  recurrence-free survival rate
• recurrences can be treated with resection in the
  absence of metastasis
• adjuvant treatment following re-resection should
  be considered for all patients who did not
  previously undergo chemotherapy
• pulmonary metastasis have median survival of 6 to
  12 months
• pulmonary metastasis resection may associated
  with prolonged survival
• hepatic metastasis survival rates have been
  lesser
• unresectable metastatic disease
• chemotherapy may provide some clinical efficacy

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• surveillance is based on low vs high grade tumor
• low-grade disease
• physical examination
• ct scan of chest, abdomen, and pelvis
• every 3 to 6 months for 2 to 3 years, then
  annually
• high-grade disease
• physical examination
• ct scan of chest, abdomen, and pelvis
• every 3 to 4 months for 3 years, then every 6
  months for 2 years, then annually

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gastrointestinal stromal tumors (GIST)

• 1-3 of all gastrointestinal malignancies
• GIST is a form of connective tissue
  cancer/sarcoma - a non-epithelial tumor
• 70 occur in the stomach
• 20 in the small intestine
• lt10 in the esophagus
• characteristics of GISTs
• spindle cells in 70-80, epitheloid aspect in
  20-30
• immunohistochemistry
• antibodies that stain the molecule CD117 (also
  known as c-kit)
• GISTs are thought to arise from interstitial
  cells of Cajal (ICC)
• normally part of the autonomic nervous system of
  the intestine
• pacemaker function in controlling motility
• Most small GISTs (lt5 and especially lt2 cm) with a
  low rate of mitosis (lt5 dividing cells per 50
  HPF) are benign
• surgery
• do not require adjuvant therapy
• Larger GISTs (gt5 cm), and especially when the
  cell division rate is high (gt6 mitoses/50 HPF)
  may be more malignant
• neoadjuvant surgery /- adjuvant