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Tumor subtype, location should guide MRI surveillance after soft tissue sarcoma excision
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Local recurrence of soft tissue sarcoma is associated with distant metastases and mortality, so prompt detection is important to ensure optimal outcomes.
There is a lack of consensus, however, about the role of MRI for surveillance after surgical excision.
More than a decade ago, Gerrand and colleagues surveyed sarcoma specialists in the United Kingdom to assess trends in follow-up after primary treatment of soft tissue sarcoma. The 155 respondents indicated their preferred frequency and method of follow-up for each of three clinical scenarios.
The results — published in Sarcoma — revealed a wide range of surveillance protocols, including clinic visits, X-rays, chest CT scans, local site imaging and blood tests. Costs of the most expensive regimens were seven to 20 times higher than those for the least expensive approaches, highlighting the significant economic consequences of practice variations.
Excessive utilization of MRI is economically inefficient, and it also may expose patients to unnecessary biopsies and procedures. At the same time, strict avoidance of MRI may lead to delayed diagnoses, resulting in increased morbidity and mortality.
MRI for extremity soft tissue sarcoma
The debate about the role of MRI intensified last fall after a podium presentation at the Connective Tissue Oncology Society (CTOS) Annual Meeting.
Jong Woong Park, MD, PhD, of National Cancer Center in Goyang-Si, South Korea, and colleagues aimed to assess the usefulness of MRI for detecting local recurrence in extremity soft tissue sarcoma. They also sought to identify the characteristics of local recurrence detected by MRI and determine whether MRI surveillance improved oncologic outcomes.
The analysis included 477 patients who underwent surgery for extremity soft tissue sarcoma. All patients received regular surveillance for local recurrence via MRI (n = 325) or other imaging modalities (n = 152).
Histologic assessment confirmed all local recurrences. Among those who underwent MRI, the mean number of scans was 7.4 (range, 1-19) and the mean interval was 6 months (range, 2-12).
Ninety-six local recurrences occurred during follow-up; of those, 34 (36%) were detected by MRI, 33 (35%) were detected by clinical examination and 27 (29%) were detected by ultrasound. Park and colleagues reported 11% of patients who underwent MRI had clinically undetectable local recurrence identified by MRI.
Results showed MRI-detected local recurrences appeared more likely than those detected by other means to be smaller (P = .002) or located in the thigh or pelvis (P = .006). MRI-detected recurrences were less likely to have mass formation (P = .007).
Patients who underwent MRI surveillance also achieved significantly longer disease-specific survival (P = .009).
“Routine MRI surveillance can detect [a] significant number of asymptomatic local recurrences in extremity soft tissue sarcoma,” Park and colleagues wrote. “Routine MRI surveillance for local recurrence may translate into better oncologic outcome in extremity soft tissue sarcoma.”
This presentation generated robust conversation and debate at the CTOS Annual Meeting. Sarcoma experts from around the world shared their past experiences and preferences for MRI surveillance after sarcoma resection.
Some argued against routine MRI surveillance, commenting on the challenges of differentiating recurrent sarcoma from postsurgical and postradiation changes, which can lead to unnecessary biopsies. They argued that not only is routine surveillance economically inefficient, but it can lead to unnecessary emotional distress for patients and families. In addition, many clinicians felt most recurrent sarcomas could be detected by clinical exam.
Others agreed with routine surveillance, emphasizing the importance of early detection of local recurrence, which may allow for curative surgical resection prior to the development of metastatic disease. However, the timeline of detection of local recurrence has not been quantified and could impact the utilization of MRI for surveillance.
All commenters acknowledged the lack of consensus recommendations due to the challenges of creating well-designed studies for sarcomas, a rare and heterogeneous group of malignancies.
Previous studies and clinical guidelines
Prior studies on this topic lacked randomized controlled data, and most of the available evidence in the literature highlight the limitations of MRI surveillance for local recurrence.
In a paper published in 2014 in Journal of Surgical Oncology, Cheney and colleagues determined periodic MRI only discovered asymptomatic local recurrence among 0.9% of patients. The authors recommended utilizing MRI only for patients whose primary tumor site is difficult to assess by history and physical exam.
Whooley and colleagues retrospectively reviewed 150 cases of extremity-based primary soft tissue sarcomas. They reported 27 (18%) local recurrences. Of these, 14 occurred within 2 years of surgery, and all but three occurred within 5 years.
Abnormal physical exam detected local recurrence among all but one patient, leading the authors to conclude MRI is ineffective. They recommended MRI be reserved for patients who have challenging body habitus or received prior radiation, or those whose tumors are in difficult-to-examine locations.
Labarre and colleagues reported MRI detected two of nine asymptomatic local recurrences but resulted in nine false positives, requiring unnecessary biopsies or procedures.
Patel and colleagues recommended periodic imaging of the lungs due to the frequency of asymptomatic pulmonary metastases. However, the opposite held true for imaging surveillance of the primary tumor site due to the efficacy of wide surgical excision combined with radiation. They recommended reserving MRI surveillance for patients at high risk for local recurrence.
John M. Kane III, MD, FACS, reviewed surveillance strategies after surgical resection of soft tissue sarcoma and determined physical exam discovered the majority of local recurrences.
In Kane’s review — published in 2004 in Current Opinion in Oncology — he suggested patients with prior radiation, extensive scar tissue, flap reconstruction and deep-seated tumors may be the most appropriate candidates for periodic imaging surveillance.
National Comprehensive Cancer Network guidelines for soft tissue sarcoma recommend considering postoperative baseline and periodic imaging for detection of local recurrence. They also recommend MRI with and without contrast or CT with contrast for local surveillance.
Ultrasound may be considered for small superficial sarcomas, but that requires serial evaluation by an experienced musculoskeletal sonographer.
The European Society for Medical Oncology recommends considering MRI or CT every 3 months to 4 months for intermediate- to high-grade tumors, and every 4 months to 6 months for low-grade sarcomas. The society’s recommendations caution that periodic imaging may detect local recurrence sooner; however, it has not been determined whether this has significant clinical implications.
Practical considerations
Creating an all-encompassing recommendation for use of MRI to detect local recurrence of soft tissue sarcoma is not practical.
Each case — and each tumor — is unique, creating individualized challenges and the potential for confounding in statistical analyses of the utility of a generalized practice.
This reality — in combination with a lack of high-quality data to provide guidance — has contributed to ambiguity in definitive surveillance protocols.
We believe the decision to utilize MRI during posttreatment surveillance of soft tissue sarcoma should be based on a case-by-case analysis of risk factors predisposing to local recurrence, as well as the potential difficulty of detection by routine clinical surveillance.
Patients who present with challenging sarcoma subtypes — such as myxofibrosarcoma — for which local recurrence rates are high are appropriate candidates for MRI surveillance.
In general, patients with surgical excision beds in challenging locations (eg, intrapelvic, deep thigh or retroperitoneal) and those who underwent flap reconstruction are good candidates for periodic local surveillance with MRI.
MRI also may be indicated for patients with a history of local recurrence, and those who may have compliance issues also could benefit from such surveillance.
There is no consensus with regard to interval or duration of local surveillance.
When MRI is indicated, we recommend periodic surveillance for intermediate- to high-grade tumors every 4 months to 6 months during the first 2 years, and then every 6 months to 12 months in years 3 through 5.
A majority of local recurrences among patients with high-grade sarcomas occur in the first 2 to 3 years. However, certain sarcoma subtypes (eg, fibromyxoid sarcoma, extraskeletal chondromyxoid sarcoma and alveolar soft part rhabdomyosarcoma) are known to have delayed local recurrences and may benefit from prolonged annual MRI surveillance.
The role of other imaging modalities is less useful.
CT scans have inferior image quality of soft tissues compared with MRI. Ultrasound can be accurate and efficient for detecting local recurrence; however, the benefit is dependent upon the skill and experience of the operator and is difficult to quantify.
Conclusion
In summary, use of periodic MRI surveillance for soft tissue sarcoma local recurrence should be guided by a case-by-case analysis based on relevant clinical data, tumor location and sarcoma subtype.
It is important for providers to remain cognizant of the statistically low chance of discovering an asymptomatic local recurrence, as well as the possibility of false positives that may lead to unnecessary procedures.
References:
Casali PG, et al. Ann Oncol. 2010;doi:10.1093/annonc/mdq209.
Cheney MD, et al. J Surg Oncol. 2014;doi:10.1002/jso.23541.
Gerrand CH, et al. Sarcoma. 2007;doi:10.1155/2007/34128.
Kane JM 3rd. Curr Opin Oncol. 2004;16:328-332.
Labarre D, et al. Eur J Radiol. 2009;doi:10.1016/j.ejrad.2009.05.027.
Mehren MV, et al. J Natl Compr Canc Netw. 2016;14:758-786.
Park JW, et al. Paper 008. Presented at: Connective Tissue Oncology Society Annual Meeting; Nov. 7-11, 2017; Wailea, Hawaii.
Patel SA, et al. Ann Surg Oncol. 2017;doi:10.1245/s10434-016-5755-5.
Whooley BP, et al. Semin Surg Oncol. 1999;17:83-87.
For more information:
Christopher N. Johnson, DO, is an orthopedic surgeon with Parkview Cancer Institute and Ortho NorthEast. He can be reached at Parkview Cancer Institute, 11141 Parkview Plaza Drive, Suite 305B, Fort Wayne, IN 46845; email: cjohnson@orthone.com.
Matthew J. Thompson, MD, is assistant professor in the department of orthopedics and sports medicine at University of Washington. He can be reached at Orthopedic Oncology Center at UWMC-Roosevelt, 4245 Roosevelt Way NE, Seattle, WA 98105; email: mthomp2@uw.edu.
Disclosures: Johnson and Thompson report no relevant financial disclosures.