High SUVmax on FDG-PET indicates pleomorphic subtype in epithelioid malignant pleural mesothelioma: supportive evidence to reclassify pleomorphic as nonepithelioid histology

Our plain-English summary of High SUVmax on FDG-PET indicates pleomorphic subtype in epithelioid malignant pleural mesothelioma: supportive evidence to reclassify pleomorphic as nonepithelioid histology, by K. Kadota, S.S. Kachala, J. Nitadori, et al (Journal of Thoracic Oncology, 2012).

The study

• Authors: K. Kadota, S.S. Kachala, J. Nitadori, K. Suzuki, M.P. Dunphy, C.S. Sima, W.D. Travis, V.W. Rusch, P.S. Adusumilli
• Journal: Journal of Thoracic Oncology
• Published: 2012;7(7):1192-7
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: We have recently proposed to reclassify the pleomorphic subtype of epithelioid malignant pleural mesothelioma (MPM) as nonepithelioid (biphasic/sarcomatoid) histology because of its similarly poor prognosis. We sought to investigate whether preoperative maximum standardized uptake value (SUVmax) on F-fluorodeoxyglucose (FDG) positron emission tomography (PET) correlates with histologic subtype in MPM.

Methods: Clinical data were collected for 78 patients with MPM who underwent preoperative FDG-PET. We retrospectively classified the epithelioid tumors into five subtypes: trabecular, tubulopapillary, micropapillary, solid, and pleomorphic. Tumors were categorized by SUVmax into two groups: low (<10.0) and high (≥10.0).

Results: The median overall survival of epithelioid tumors with high SUVmax (n = 12) was significantly shorter (7.1 months) than that of epithelioid tumors with low SUVmax (n = 54, 18.9 months, p < 0.001) and comparable to nonepithelioid tumors (n = 12, 7.2 months). Epithelioid tumors with pleomorphic subtype (n = 9) had marginally higher SUVmax (mean ± SD: 10.6 ± 5.9) than epithelioid nonpleomorphic subtype (n = 57, 6.5 ± 3.2, p = 0.050), and were comparable to that of nonepithelioid tumors (n = 12, 9.1 ± 4.8). Among the epithelioid tumors with high SUVmax (n = 12), 50% (n = 6) showed pleomorphic subtype. In contrast, among epithelioid tumors with low SUVmax (n = 54), 6% (n = 3) showed epithelioid pleomorphic subtypes (p = 0.001). A positive correlation between mitotic count and SUVmax was observed (r = 0.30, p = 0.010).

Conclusions: Pleomorphic subtype of epithelioid MPM showed higher SUVmax than the epithelioid nonpleomorphic subtype and was similar to nonepithelioid histology. Preoperative SUVmax on FDG-PET in epithelioid MPM can indicate patients with pleomorphic subtype with poor prognosis, supporting their reclassification as nonepithelioid.

In plain English

This retrospective study reviewed 78 patients with malignant pleural mesothelioma, diagnosed 1998 to 2009 at Memorial Sloan-Kettering Cancer Center, who had an FDG-PET scan before surgery. Of these, 66 had epithelioid tumors and 12 had nonepithelioid (biphasic or sarcomatoid) tumors. The authors compared tumor uptake of the PET tracer (SUVmax: low, under 10; high, 10 or more) with microscopic tumor subtype and survival. The article does not report asbestos exposure. Among epithelioid tumors, median overall survival was 7.1 months with high SUVmax (12 patients) versus 18.9 months with low SUVmax (54), similar to 7.2 months for nonepithelioid tumors. Pleomorphic tumors had a mean SUVmax of 10.6, marginally higher than 6.5 for other epithelioid subtypes (p = 0.050). Half of high-SUVmax epithelioid tumors (6 of 12) were pleomorphic, compared with 6% (3 of 54) of low-SUVmax ones. Higher SUVmax correlated with higher mitotic count. The authors concluded that high SUVmax correlates with the pleomorphic subtype, which they saw as support for reclassifying it as nonepithelioid. They noted that scans came from several sites and scanners, and that the findings need prospective confirmation.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective study of patients treated at a single cancer center, comparing preoperative FDG-PET SUVmax with tumor histology and survival
• Who was studied: 78 patients diagnosed with malignant pleural mesothelioma (MPM) between 1998 and 2009 at Memorial Sloan-Kettering Cancer Center who had FDG-PET before surgery. Of these, 66 had epithelioid tumors and 12 had nonepithelioid tumors (6 biphasic, 6 sarcomatoid).
• Exposure: No asbestos or fiber exposure is reported. The factor studied was preoperative maximum standardized uptake value (SUVmax) on FDG-PET, grouped as low (less than 10) or high (10 or more), in relation to histologic subtype (trabecular, tubulopapillary, micropapillary, solid, pleomorphic).
• Main results:
  • Epithelioid tumors with high SUVmax (n = 12) had a median overall survival of 7.1 months, versus 18.9 months for epithelioid tumors with low SUVmax (n = 54, p less than 0.001). This was comparable to nonepithelioid tumors (n = 12, 7.2 months).
  • After excluding the 9 pleomorphic cases, epithelioid tumors with high SUVmax (n = 6) had a median overall survival of 5.6 months, versus 19.4 months with low SUVmax (n = 51, p = 0.005).
  • Among 44 patients with completely resected epithelioid tumors, median time to recurrence was 14.4 months with high SUVmax (n = 7) versus 21.9 months with low SUVmax (n = 37, p = 0.047).
  • Within epithelioid tumors, the pleomorphic subtype (n = 9) had the highest SUVmax (mean plus or minus SD 10.6 plus or minus 5.9).
  • The pleomorphic subtype's SUVmax was marginally higher than that of epithelioid nonpleomorphic subtypes (n = 57, 6.5 plus or minus 3.2, p = 0.050).
  • Nonepithelioid tumors (n = 12, 9.1 plus or minus 4.8) seemed to have higher SUVmax than all epithelioid tumors (n = 66, 7.1 plus or minus 3.9). The difference was not statistically significant (p = 0.160).
  • The SUVmax of nonepithelioid tumors was significantly higher than that of epithelioid nonpleomorphic subtypes (p = 0.046).
  • Among epithelioid tumors with high SUVmax (n = 12), 50% (n = 6) were the pleomorphic subtype.
  • Among epithelioid tumors with low SUVmax (n = 54), 6% (n = 3) were the pleomorphic subtype (p = 0.001 for the comparison with high-SUVmax tumors).
  • In epithelioid tumors, mitotic count showed a moderate correlation with SUVmax (r = 0.30, p = 0.010).
  • In epithelioid tumors, necrosis of 10% or more was significantly associated with higher SUVmax (p = 0.042).
  • Among patients scanned at Memorial Sloan-Kettering, epithelioid tumors with high SUVmax (n = 7) had a median overall survival of 8.9 months, versus 19.4 months with low SUVmax (n = 36, p less than 0.001).
• The authors' conclusion: The authors concluded that high SUVmax correlates with the pleomorphic subtype in epithelioid MPM, showing a radiologic resemblance between the pleomorphic subtype and nonepithelioid tumors. They saw this as support for reclassifying the pleomorphic subtype as nonepithelioid, and stated that epithelioid MPM with high SUVmax should be considered as having a poorer prognosis.
• Limitations the authors state:
  • The PET scans were performed at multiple locations.
  • At Memorial Sloan-Kettering, four different scanners were used, and SUV values differed between scanners, attenuation corrections and acquisition modes.
  • The study was retrospective, and the authors stated that the findings should be validated prospectively.
  • It is difficult to match the pleomorphic area seen under the microscope precisely to the site of SUVmax on the PET scan.
  • In the Memorial Sloan-Kettering subgroup, the small sample size did not allow statistical comparison of SUVmax between subtypes.
  • Total glycolytic volume, which another group found to be prognostic, was not recorded.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleomorphic, Epithelioid, Pleural Mesothelioma, Histology, Biphasic Mesothelioma, Sarcomatoid, Prognosis, Histological Subtype.

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• Tumoral CD10 expression correlates with aggressive histology and prognosis in patients with malignant pleural mesothelioma — K. Kadota, J. Villena-Vargas, et al. (2015)
• Impressive clinical response to anti-PD-1 therapy in epithelioid mesothelioma with high clonal PD-L1 expression and EML4-ALK rearrangement — G. Bronte, A. Delmonte, et al. (2020)
• Shorter Survival in Malignant Pleural Mesothelioma Patients With High PD-L1 Expression Associated With Sarcomatoid or Biphasic Histology Subtype: A Series of 214 Cases From the Bio-MAPS Cohort — S. Brosseau, C. Danel, et al. (2019)
• Chronic inflammation in tumor stroma is an independent predictor of prolonged survival in epithelioid malignant pleural mesothelioma patients — K. Suzuki, K. Kadota, et al. (2011)
• Pleural fluid cytological yield and visceral pleural invasion in patients with epithelioid malignant pleural mesothelioma — V. Pinelli, S. Laroumagne, et al. (2012)

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