Marginal Excision of Low‐Grade Spindle Cell Sarcoma of Canine Extremities: 35 Dogs (1996–2006)

Abstract

Objective-To evaluate recurrence rate and disease-free interval (DFI) of dogs with low-grade soft tissue spindle cell sarcoma of the extremities treated by marginal excision. Study Design-Retrospective study. Animals-Dogs (n ¼ 35) with soft tissue low-grade spindle cell sarcoma. Methods-Medical records were reviewed and dogs that had marginal surgical resection of lowgrade soft tissue spindle cell sarcoma at or distal to elbow and stifle were included. Results-Histopathologic margins were dirty (12 dogs), clean but close (12), and clean (11). Followup after surgery occurred from 210 to 2202 days (minimum, 180 days). Local recurrence and metastatic rates were 10.8% and 0%, respectively. Median DFI and survival time were not reached, because o50% of dogs died of disease-related events. Mean DFI and mean survival time were 697.8 days (95% CI: 559.7-836 days) and 703.5 days (95% CI: 566.6-840.5 days), respectively. There were no significant differences among survival functions stratified by histologic margins. Conclusion-Marginal surgical excision without adjuvant treatment of low-grade soft tissue spindle cell sarcoma of the extremities results in a low local recurrence rate. Clinical Relevance-Low-grade spindle cell sarcomas located at or distal to the elbow and stifle joints can be excised without need for wide or radical surgery. r

Prognostic Factors for Cutaneous and Subcutaneous Soft Tissue Sarcomas in Dogs

“…In addition, most studies evaluating prognostic factors for canine STS were conducted retrospectively. 3,5,7,11,23,32,46,[48][49][50] These studies can be troubled by a variety of biases and limitations, 55 including loss to follow-up, inability to review original slides, 11 lack of standard treatment and/or follow-up protocols, inability to confirm metastasis, and inability to provide accurate measurements of tumor size. 48 Another common drawback of STS prognostication studies is a lack of multivariable analysis.…”

“…A relationship between degree of resection and survival has yet to be clearly demonstrated. Although it has been explored by several studies 10,11,39,50 and is a significant prognostic factor for survival on univariable analysis of dogs with liposarcoma, 4 robust studies are needed that include an adequate number of events for the level of prognostic variables examined in multivariable analysis. The lack of a sizable influence of degree of resection on patient survival would call to question the need for radical treatment, such as amputation, unless the tumor is causing physical impairment of the patient.…”

“…These neoplasms-including histiocytic sarcoma, lymphangiosarcoma, hemangiosarcoma, synovial cell sarcoma, leiomyosarcoma, rhabdomyosarcoma, fibrosarcomas involving the oral cavity, and brachial plexus peripheral nerve sheath tumors (PNSTs; also termed schwannomas, neurofibromas, 12 or nerve sheath tumors 16 )-are specifically excluded from STS grouping because they can be consistently distinguished by microscopic features and/or anatomical location and because as a group, they exhibit more malignant biological behavior. 8,11,17,19,32,33,35,40,50 Thus, when applied to canine tumors of the skin and subcutis, the term soft tissue sarcoma is a grouping of tumors that is becoming a diagnosis of exclusion. This is in contrast to the grouping scheme for human STSs, which is not exclusionary.…”

“…Close margins: Distance between surgically created tissue edge and neoplastic cells is less than 3 mm thickness, 50 or surgical margins do not contain normal tissue outside the pseudocapsule.…”

“…48 Another common drawback of STS prognostication studies is a lack of multivariable analysis. 4,5,7,11,20,25,37,40,46,49,50 In these studies, numerous prognostic variables were explored independently without adjusting for the effects of other prognostic variables. There is some disparity in the way in which canine STSs are grouped among studies.…”