Histology-based Classification Predicts Pattern of Recurrence and Improves Risk Stratification in Primary Retroperitoneal Sarcoma

Abstract

Objective To determine the prognostic significance of histologic type/subtype in a large series of patients with primary resected retroperitoneal sarcoma. Summary Background Data The histologic diversity and rarity of retroperitoneal sarcoma has hampered the ability to predict patient outcome. Methods From a single-institution, prospective database, 675 patients treated surgically for primary, non-metastatic retroperitoneal sarcoma during 1982–2010 were identified and histologic type/subtype was reviewed. Clinicopathologic variables were analyzed for association with disease-specific death (DSD), local recurrence (LR), and distant recurrence (DR). Results Median follow-up for survivors was 7.5 years. The predominant histologies were well-differentiated liposarcoma, dedifferentiated liposarcoma, and leiomyosarcoma. Five-year cumulative incidence of DSD was 31%, and factors independently associated with DSD were R2 resection, resection of ≥3 contiguous organs, and histologic type. Five-year cumulative incidence for LR was 39% and for DR was 24%. R1 resection, age, tumor size, and histologic type were independently associated with LR; size, resection of ≥3 organs, and histologic type were independently associated with DR. Liposarcoma and leiomyosarcoma were associated with late recurrence and DSD (as long as 15 years from diagnosis). For solitary fibrous tumor, local recurrence was uncommon (<10%), but early distant recurrence was common (36% at 5 years). Nomograms were developed to predict DSD, LR, and DR. Conclusions Histologic type/subtype is the most important independent predictor of DSD, LR, and DR in primary retroperitoneal sarcoma. Histology predicts the pattern and incidence of LR and DR and will aid in more accurate patient counseling and selection of patients for adjuvant therapy trials.

Salvage Surgery for Recurrent Retroperitoneal Well-Differentiated Liposarcoma: Early Reoperation may not Provide Benefit

“…5,6,15 However, currently available evidence for recurrent RP sarcomas supporting salvage resection generally lacks detailed histology-specific analyses, which make it difficult to apply those data to patients with recurrent RP WDLPS. 7–9,11,16–18 The survival impact of salvage surgery must differ between histologic subtypes, but no previous study included interaction (effect modification) terms in multivariable models, or they were underpowered to do so.…”

“…1 RP sarcomas comprise various histologic subtypes, 2 and liposarcoma is the most common among them. 3,4 Each histologic subtype has a distinct recurrence pattern 5 ; therefore, reports that do not specify histology may not effectively guide treatment strategy. 6 For example, leiomyosarcoma has a high risk of distant metastasis (>50%) and a low risk of local recurrence (10–15%).…”

“…6 For example, leiomyosarcoma has a high risk of distant metastasis (>50%) and a low risk of local recurrence (10–15%). 4,5 In contrast, RP well-differentiated liposarcoma (WDLPS) has a high risk of local recurrence and rarely metastasizes. 4 Reports combining these two distinct histologies cannot effectively guide treatment of either.…”

Minimally Invasive Surgery for Retroperitoneal Sarcoma: Just Because We Can Does Not Mean We Should

“…These tumors are almost invariably large at presentation, with a median size of 20 cm. 5,6 Indeed MIS was used for tumors smaller, on average, than those treated with open surgery (10.5 vs. 17 cm); however, in the MIS group, the upper interquartile range value was 18.5 cm. What is the real reason for approaching an 18.5 cm tumor with MIS, when the incision to remove the specimen will inevitably be much longer (at least as long as the longer of the two cross-sectional dimensions, plus any associated peripheral organs)?…”

“…3 There is a growing body of evidence regarding the better outcome, specifically among RPS patients initially treated in specialized centers. [4][5][6][7] This disease, or in reality, family of diseases, is complex. There are several histological subtypes, which have different behavior and risks.…”