Editing Soft tissue sarcoma (section)

=== '''Retroperitoneal''' ===

** Often >15cm at diagnosis
** Present with pain, weight loss, early satiety, nausea, emesis, back or flank pain, paraesthesias and weakness
** Most common subtypes are liposarcoma, leiomyosarcoma, and undifferentiated pleomorphic sarcoma
** DDx - lymphoma (peripheral lymphadenopathy and constitutional symptoms), primary germ cell tumour, testicular cancer metastatic to retroperitoneal nodes (need testicular examination + AFP and bHCG)
** Imaging alone rarely diagnostic
** Locoregional recurrence is most common pattern, rather than distant
** Patients with complete gross resection have a median survival of 103 months, as opposed to 18 months for patients with incomplete resections. Patients with unresectable tumours have a median survival of 10 months. 
** Biopsy
*** Most retroperitoneal masses should ideally be biopsied prior to treatment, although this is not always necessary
*** The main thing is to exclude major differentials as above - if it's possible to exclude these based on imaging/clinical history, then biopsy may not be necessary
*** Core needle under USS/CT is best - biopsy tract seeding is rare
** Excision is indicated when feasible
*** Needs to be R0 at first attempt - no chance for second attempt. No benefit to incomplete resection since patients with positive margins have the same survival rates as patients who were initially unresectable.
*** If needed, pancreatic tail, spleen, ipsilateral kidney (be sure to assess contralateral renal function), colon and mesocolon and at least a portion of psoas can be safely resected
*** More significant resections would involve vasculature, liver, femoral nerve, diaphragm, duodenum
*** Incision could be midline, oblique, flank or thoracoabdominal
*** Incomplete resection of well-differentiated liposarcomas seems to help regardless of persisting tumour
** Chemotherapy
*** Controversial - better in neoadjuvant setting when it's used
*** Clinical trials a possibility
*** Few effective treatment options for metastatic disease
** Radiotherapy
*** Controversial - not been proven to reduce risk of recurrence, and risk of damage to viscera. The doses given to extremity STS would cause significant bowel toxicity. 
*** Favoured to be done pre-op when used - allows better targeting to posterior structures, can still manage 45Gy, with boosts to projected at-risk margins. Long and short-term oncologic outcomes are favourable.
** Surveillance
*** Continue up to and beyond five years