|Year : 2016 | Volume
| Issue : 3 | Page : 408-411
Does magnetic resonance imaging accurately predict residual disease after unplanned excision of soft-tissue sarcomas?
S Patkar1, A Gulia2, S Juvekar3, B Rekhi4, A Puri2
1 Department of Surgical Oncology, Tata Memorial Hospital, Mumbai, Maharashtra, India
2 Department of Orthopedic Oncology, Tata Memorial Hospital, Mumbai, Maharashtra, India
3 Department of Radiodiagnosis, Tata Memorial Hospital, Mumbai, Maharashtra, India
4 Department of Pathology, Tata Memorial Centre, Mumbai, Maharashtra, India
|Date of Web Publication||24-Feb-2017|
Department of Orthopedic Oncology, Tata Memorial Hospital, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
BACKGROUND: Often, it is difficult to assess the presence of residual disease after an unplanned excision in soft-tissue sarcomas. Inadequate excision leads to disease recurrence and inferior oncological outcomes while unnecessary excision may lead to additional surgical procedures with inherent morbidity and increased cost of treatment. There is a paucity of literature comparing the preoperative imaging findings with the final histopathology report to accurately assess the presence of residual disease. MATERIALS AND METHODS: The clinical details of 55 patients who had oncological scar excision after unplanned prior excision were retrieved. Histopathological evaluation of scar was compared with presurgery magnetic resonance imaging (MRI) for the presence of residual disease. Sensitivity, specificity, and positive and negative predictive value (NPV) of MRI for detection of residual disease were calculated. RESULTS: On MRI, residual disease was seen in 28 cases, no disease in 24 cases whereas findings of three patients were indeterminate. On final histopathology, residual disease was present in 30 (55%) patients whereas no residual tumor was seen in 25 (45%) patients. Two patients in whom MRI suggested the presence of residual disease had no tumor on final histopathology. No evidence of residual disease was reported in MRI of 24 patients. Of these, twenty patients were confirmed to have no tumor on final histopathology, whereas four patients had a residual tumor. Sensitivity: 86.66%, specificity: 90.90%, positive predictive value (PPV): 92.85%, NPV: 83.33%. CONCLUSION: MRI can aid in preoperative planning by identifying the site and extent of the previous surgery. It has a high PPV (92%) for detection of residual disease. However, a negative scan (NPV 83%) does not reliably exclude the presence of residual disease.
Keywords: Magnetic resonance imaging, soft-tissue sarcomas, unplanned excision
|How to cite this article:|
Patkar S, Gulia A, Juvekar S, Rekhi B, Puri A. Does magnetic resonance imaging accurately predict residual disease after unplanned excision of soft-tissue sarcomas?. Indian J Cancer 2016;53:408-11
|How to cite this URL:|
Patkar S, Gulia A, Juvekar S, Rekhi B, Puri A. Does magnetic resonance imaging accurately predict residual disease after unplanned excision of soft-tissue sarcomas?. Indian J Cancer [serial online] 2016 [cited 2017 Jul 27];53:408-11. Available from: http://www.indianjcancer.com/text.asp?2016/53/3/408/200670
| » Introduction|| |
Soft-tissue sarcomas (STS) are a rare group of malignancies comprising only 1% of all malignancies in adults, with an overall incidence of 2–3/100,000/year., Central to the treatment of STS is oncologically sufficient surgical resection of the tumor. The rarity of STS often results in them being undertreated or inappropriately excised by surgeons outside of specialist sarcoma units.,,
The management of the patient referred after an unplanned excision of STS is based on a thorough review of the clinical and radiological information. This would include details of any preoperative investigation, specifics of the surgical procedure from the referring surgeon, and a review of the histology and the margins of excision. Depending on the collective interpretation of this information and the potential morbidity of any further surgery, the options include no further surgery, re-excision of residual tumor or scar (in most cases of unknown or involved margins), and consideration of adjuvant chemotherapy and/or radiotherapy. Re-excisions result in increased morbidity, an additional surgical procedure and increase in the cost of overall treatment. Thus, a judicious selection of patients needing re-excision is warranted to optimally balance oncological outcomes against the outlined disadvantages.
There is a paucity of literature comparing the accuracy of preoperative imaging findings in predicting residual tumor on the final histopathology report.,
The present study assesses the correlation between preoperative magnetic resonance imaging (MRI) findings and final histopathology report in cases of scar excision/revision performed for high-grade sarcomas with prior unplanned excision. The main objective was to determine if preoperative MRI could reliably detect the presence of residual disease.
| » Materials and Methods|| |
Consecutive patients above the age of 12 years with a history of unplanned excision of high-grade STS (within the previous 3 months) with unknown or positive margin status who underwent re-excision surgery were included in the study.
- Patients undergoing per primum excision
- Previous surgery performed more than 3 months back
- History of prior irradiation
- Low-grade sarcomas.
The study was approved by the Institutional Review Board of our institution.
Data were retrospectively retrieved from a prospectively maintained database. Additional information was retrieved from the case files, electronic medical records, and imaging sources.
A total of 55 patients with a mean age of 40 years (range: 18–72) were included in the study. There were 30 male (55%) and 25 (45%) female patients with a ratio of 1.2:1. The majority of the cases were in the extremity accounting for 53 out of 55 patients (97%), of which 44 (80%) occurred in the lower extremity and 9 (17%) occurred in the upper extremity. Two (3%) cases were located on the back.
Preoperative imaging had been performed in only ten patients before index surgery. One patient had positive margins, while margins were not commented on in the other 54 cases. There were varied histology subtypes in this cohort. The predominant histology was synovial sarcoma in ten patients followed closely by spindle cell sarcoma in nine patients. Dermatofibrosarcoma was seen in three patients. Two patients each of leiomyosarcoma and myxofibrosarcoma and one each of epitheloid sarcoma, malignant peripheral nerve sheath tumor (MPNST), liposarcoma and clear cell sarcoma were reported [Table 1].
Our protocol has been to advise most patients with high-grade sarcomas who have been managed with unplanned excision and who have unknown or positive resection margins to undergo an oncologically appropriate resection at the previous operative site with adjuvant irradiation. Before surgery, a thorough clinical and radiological evaluation was done to identify any residual disease. Radiological evaluation of local disease site was done with MRI. Imaging protocol included the acquisition of images in T1-weighted axial, fat saturated T2-weighted coronal and T2-weighted sagittal, fat saturated T1-weighted unenhanced axial and fat saturated T1-weighted sequences contrast enhanced in axial and coronal planes. STSs reveal intermediate signal intensity on T1-weighted images compared to skeletal muscle and show high signal intensity on T2-weighted images, and solid components in STSs show postcontrast enhancement.
All the imagings were reported by a senior radiologist specialized in musculoskeletal oncology (SJ). Before surgery, a radiological impression documenting the presence or absence of residual disease was recorded. Residual disease was identified as such by a focal mass that was typically of high signal on T2-weighted and short-time inversion recovery sequences. Postoperative fibrosis (scar tissue) typically demonstrated low signal intensity on both T1- and T2-weighted sequences (similar to muscle) and showed little or no enhancement with gadolinium.
All the patients were staged as per the hospital protocol with a contrast tomography scan of the thorax to rule out metastatic disease. All the cases were clinically evaluated and operated by musculoskeletal oncosurgeons (AP, AG).
After excision, the specimens were evaluated by one of the coauthors (BR) for the presence of disease and margin status. Based on the final histopathology report, the data were analyzed to detect the accuracy and reliability of imaging in detecting the presence of residual disease at the site of surgery. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of MRI in the detection of residual disease were determined.
| » Results|| |
The average time interval between the index surgery and MRI was 34 days. The median interval was 30 days. In all the MRI performed before scar revision, residual disease was seen in only 28 cases, no disease in 24 cases, whereas 3 patients were indeterminate. Contrast-enhanced images were available in 41 patients, whereas 14 had no contrast.
The mean duration between index surgery and scar revision was 61 days and a median of 60 days.
Soft-tissue defect in 39 patients could be closed primarily. In 16 (27%) patients, additional procedures including major flaps were required to achieve wound closure. All patients had a negative margin on final surgical resection. Of the 55 patients, 9 patients were suitable for interstitial brachytherapy and remaining had adjuvant radiotherapy.
The radiology findings and their correlation with the final histopathology report was analyzed. Residual disease was identified on imaging in 28 patients and presence of residual tumour was confirmed on final histopathology in 26 patients. Two patients with MRI suggestive of presence of residual disease had no tumour on final histopathology.
No evidence of residual disease was reported in imaging findings of 24 patients where as findings of three patients were indeterminate.
Of the 24 patients whose imaging was negative for residual disease, 20 patients were confirmed to have no tumour on final histopathology. In case of 4 patients residual tumour was present.
Of the three patients with indeterminate findings on imaging, none had evidence any tumour on final histopathology.
The sensitivity of MRI for detecting residual disease was 86.66% and specificity 90.90% with a PPV of 92.85% and an NPV of 83.33%. The accuracy of MRI was 88.46%.
A subset analysis of the use of contrast versus noncontrast imaging did not reveal any significant difference. The PPV remained high irrespective of the use of contrast, and the NPV did not change in the two groups.
| » Discussion|| |
Unplanned resection of a sarcoma has been discussed in several previous reports. Giuliano and Eilber  were the first authors to describe the term “unplanned total excision,” meaning excisional biopsies for presumed benign diseases. Noria et al. further defined the term “unplanned resection of a sarcoma” as an excisional biopsy or unplanned resection of a lesion without the benefits of preoperative imaging and without regard for the necessity of removing the lesion with a margin of normal tissue. Unplanned excisions of STSs occur frequently and several studies have reported better local control in patients who underwent tumor bed excision after such misadventures than in patients who did not.,,,,,,
Hoshi et al. demonstrated the adverse oncologic outcome of unplanned resection and also showed the efficacy of appropriate salvage treatment in these cases to improve outcomes. The 5-year survival rate of 76.3% was almost equivalent to those for sarcomas excised in one resection, suggesting a significant role of additional wide resection in improving the treatment outcomes of unplanned resections compared with insufficient treatment without additional wide resection. It is often difficult to assess accurately the initial pathological margins of the resection and to estimate the extent of tumor that remains at the site of an unplanned excision. In such situations, it may be safer to manage the patient with high-grade sarcoma with re-excision. Re-excision leads to wider resection than necessary compared to if initial appropriate surgery had been done. This may result in wider excision of soft tissue requiring additional surgery leading to increased operative time and morbidity and inferior functional outcomes.,,
Thus, it is essential to strike a balance between achieving adequate oncological clearance and avoiding unnecessary surgeries with additional morbidity. Such additional surgeries also increase the cost of treatment. It would be beneficial if imaging can accurately predict the presence of disease in unplanned excision. In the immediate postoperative situation, there is often extensive signal abnormality in the soft tissues, and unless there is a large residual mass, it is impossible to differentiate inflammatory tissue from the residual tumor. Surgical resection in these cases may yield residual tumor in only 45%–59% of cases., In cases of inadequate initial excision, repeat surgery can be challenging as it is difficult to locate the original tumor borders and the required margins are therefore hard to define. Earlier studies too have attempted to evaluate the utility of MRI in planning re-excision. Kaste et al. found that MRI was unreliable in detecting the need for additional resection when incomplete resection had been performed for an STS. They opined that because the incidence of residual tumor is high despite negative or indeterminate findings on MRI, wide re-excision is indicated after unplanned excision of sarcoma irrespective of findings on MRI. Although positron emission tomography scan may aid in the detection of metastatic disease, it is unlikely to add further information to aid decision-making.,
Siebenrock et al. reported that MRI has a poor NPV for the identification of residual tumor following unexpected resection of an STS. A number of workers have identified the relatively high prevalence of tumor-positive margins at repeat excision. According to James et al., MRI may be helpful in detecting the relationship of any significant residual sarcoma to adjacent neurovascular structures, but it stressed that it could not detect microscopic areas of the residual tumor.
Puhaindran et al. reported that MRI does not reliably detect residual gross or microscopic STS after marginal excision of unsuspected soft-tissue sarcomas of the hand, with residual tumor not readily distinguished from postoperative change with a low PPV of 69%. Contrast-enhanced images were used for all patients. They concluded that the absence of disease on MRI should not be used as the sole criterion in determining whether a repeat resection should be performed (NPV 70%).
The largest of the studies by Davies et al. which analyzed 111 patients reported that although MRI has a high PPV (93%), a negative scan does not exclude residual tumor with a low NPV of 67%. Nevertheless, MRI is useful in preoperative planning by identifying the site and extent of the previous surgery. They concluded that the optimum treatment for all STSs would be a wide primary excision, but failing that, MRI followed by wide re-excision is the management of choice.
Our study had a sensitivity of 86.66% and specificity of 90.90% of MRI for detecting the presence of residual disease following unplanned excision of STSs. We had a PPV of 92.85% and an NPV of 83.33%. When we look at literature [Table 2], the specificity of MRI as a predictive tool has not changed over the years even with the advent of newer generation scanners.,,, In spite of the fact that the mean time interval between the index surgery and MRI in our study was 34 days (median 30) with a range between 3 and 83 days compared to 43 days as reported by Kaste et al. and 59 days by Puhaindran et al., the values are similar. Thus, differentiating between residual tumor and postsurgical changes remains a challenge irrespective of when MRIs are performed after prior inappropriate surgery.
| » Conclusion|| |
MRI remains a valuable tool before revision surgery performed after unplanned excisions. It can aid in preoperative planning by identifying the site and extent of the previous surgery. Although it has a high PPV (92%) for detection of residual disease, a negative scan does not reliably exclude the presence of residual disease. Our recommendation is that the presence of residual disease on MRI scan definitely warrants re-excision of the scar. Where MRI does not show a residual tumor, a patient-specific decision can be made based on the extent and morbidity of surgery or option of offering irradiation alone. For patients who undergo scar revision, an additional advantage is that it offers an opportunity for insertion of interstitial brachytherapy needles for focused radiotherapy delivery wherever feasible.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]