5 PROGNOSIS


5.1 Natural history

5.1.1
The natural history of soft tissue sarcomas includes a local phase and a distant phase. Low grade soft tissue sarcomas mainly entail a risk of local relapse, even after quite long time intervals. High grade soft tissue sarcomas can recur locally, but have also a high propensity to give rise to distant metastases. Since low grade sarcomas may dedifferentiate, they entail some risk of distant spread, too. Occasionally they may metastatize even without undergoing a process of dedifferentiation.

5.1.2
At the local level, low grade soft tissue sarcomas give rise to masses which look grossly demarcated by a pseudocapsule. Pathologically, this pseudocapsule is perforated by the tumor, and satellites of vital tumor can therefore be found beyond it. Therefore, these satellites should be excised by means of something more than a marginal excision. High grade sarcomas give rise, in addition to satellites, also to "skip lesions", outside the reactive zone near the pseudocapsule. Surgical excision should therefore be wider than for low grade soft tissue sarcomas. If an amputation or a compartmental resection are not performed, radiotherapy is a widely resorted option. Overall, sarcomas tend to spread along longitudinal planes, while fascial planes, nerves, vessels and bones represent quite effective anatomical barriers.

5.1.3
Lymph node metastases are rare, even if some histotypes (epithelioid sarcomas, synovial cell sarcomas, and others) are associated with a higher probability (>10-20%) of spreading to regional lymph nodes. It is widely felt that lymph node metastases are a poor prognostic factor.

5.1.4
Systemically, soft tissue sarcomas, especially high grade sarcomas, tend to metastatize to the lungs in most cases, without any concurrent lesion to other sites (so called "isolated" lung metastases). In fact, the first metastases are isolated to the lungs in as high as 80of cases. After a complete excision of isolated lung metastases, further relapses may again be isolated to the lungs. Metastatic spread can also be found to the bones, liver and distant soft tissues. Brain metastases are exceedingly rare, but may increase with aggressive surgical and medical treatment policies in the advanced disease.


5.2 Prognostic factors

5.2.1
The malignancy grade is the main prognostic factor in soft tissue sarcomas. The long term overall survival is expected to be >80-90in grade 1 sarcomas, as opposed to <40-50in grade 3 sarcomas. Grade 2 soft tissue sarcomas have an intermediate long term survival. In addition grade 3 sarcomas tend to recur earlier, i.e. in less than 2 years in most relapsing patients, than grade 2 sarcomas. Due to the coexistence of different malignancy grades within the same histotype, and the high number of different histotypes, histotype is less reliable as a prognostic factor than malignancy grade.

5.2.2
Tumor diameter is another important prognostic factor. As long as it increases, the prognosis gets worse. A conventional cuto-ff is generally set to 5-8 cm.

5.2.3
Deepness of the lesion may be a prognostic factor. In particular, it may divide grade 2 tumors into two groups: the superficial ones, with a long term survival close to grade 1 tumors, and the deep ones, with a long term survival close to grade 3 sarcomas.

5.2.4
Primary tumor site is a prognostic factor inasmuch as tumors arising in the trunk may easily reach great dimensions before giving rise to clinical symptoms. These tumors are more difficult to operate on, by comparison with limb sarcomas. In fact, they are generally not compartmental and surgical margins tend to be less adequate.

5.2.5
Other prognostic factors are currently being explored and some of them may turn out to be independent of grade, deepness and dimensions, such as, for example, tumor DNA content.


5.3 Predictive factors

5.3.1
From the surgical point of view, malignancy grade is a predictive factor for the presence of skip lesions outside the reactive zone and thereby for inadequacy of limited surgery. This prompts the surgeon to resort either to compartmental resections or to integrated radiosurgical approaches in high grade sarcomas.

5.3.2
From the medical point of view, malignancy grade may be a predictive factor of response to chemotherapy. High grade tumors would seem to respond better to chemotherapy than low grade ones. This may be less relevant in the metastatic disease, in which, by definition, malignancy grade cannot be considered truly low.


References

5.I
Daugaard S, van Glabbeke M, Schiodt T, Mouridsen H. Histopathological grade and response to chemotherapy in advanced soft tissue sarcomas. Eur J Cancer 1993; 29A:811-813.

5.II
Drobnjak M, Latres E, Pollack D, Karpeh M, Dudas M, Brennan MF, et al. Prognostic implications of p53 nuclear overexpression and high proliferation index of Ki-67 in adult soft-tissue sarcomas. J Natl Cancer Inst 1994; 86: 549-554.

5.III
Gustafson P, Rooser B, Rydholm A. Is there no influence of local control on the rate of metastases in high grade soft tissue sarcoma? Cancer 1990; 65: 1727-1729.

5.IV
Heise HW, Myers MH, Russell WO, et al. Recurrence-free survival time for surgically treated soft tissue sarcoma patients: multivariate analysis of five prognostic factors. Cancer 1988; 57: 172-177.

5.V
Mandard AM, Petoit JF, Marnay J, et al. Prognostic factors in soft tissue sarcoma: a multivariate analysis of 109 cases. Cancer 1989; 63: 1437-1451.

5.VI
Mazeron JJ, Suit HD. Lymph node as sites of metastases from sarcomas of soft tissue. Cancer 1987; 60: 1800-1808.

5.VII
Ravaud A, Bui NB, Coindre JM, Lagarde P, Tramond P, Bonichon F, et al. Prognostic variables for the selection of patients with operable soft tissue sarcomas to be considered in adjuvant chemotherapy trials. Br J Cancer 1992; 66: 961-969.

5.VIII
Ruka W, Emrich LJ, Driscoll DL, Karakousis CP. Prognostic significance of lymph node metastasis and bone, major vessel, or nerve involvement in adults with high-grade soft tissue sarcomas. Cancer 1988; 62: 999-1006.

5.IX
Stotter AT, A'Hern RP, Fisher C, Mott AF, Fallowfield ME, Westbury G. The influence of local recurrence of extremity soft tissue sarcoma on metastasis and survival. Cancer 1990; 65: 1119-1129.

5.X
Ueda T, Aozasa K, Tsujimoto M, Hamada H, Hayashi H, Omo K, et al. Multivariate analysis of clinical prognostic factors in 163 patients with soft tissue sarcoma. Cancer 1988; 62: 1444-1450.

5.XI
Van Haelst-Pisani CM, Buckner JC, Reiman HM, Schaid DJ, Edmonson JH, Hahn RG. Does histologic grade in soft tissue sarcoma influence response rate to systemic chemotherapy? Cancer 1991; 68: 2354-2358.



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European School of Oncology, 1996

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