- Email: [email protected]
A Practical Guide to Measure “All” Malignant Pleural Mesothelioma Tumors by Modified RECIST Criteria?
Journal of Thoracic Oncology • Volume 6, Number 12, December 2011
this study, but we decided to leave them out to enhance the reliability of the results. As mentioned in the article, this study is a retrospective study, due to which it has limitations.1 We tried to improve the data homogeneity, however, by applying strict inclusion criteria as much as we could to overcome the effect of differences in the treatments between the past and the present. The main topic of our article was the necessity of adjuvant radiation therapy in the completely resected invasive thymoma, including stages II and III thymoma. Furthermore, unlike in the study of Venuta et al, we did not cover thymic carcinoma and incompletely resected tumors in the study.2 It would be difficult to compare our article with the article on the results of the study by Venuta et al. because the characteristics of the tumor are very different. It is well known that in an inoperable thymoma or thymic carcinoma, chemotherapy might be needed in the neoadjuvant/adjuvant setting. However, both were not the objects of this study. Therefore, it was not important to mention chemotherapy. Moreover, it is difficult to tell the relationship between chemotherapy and its absence after metachronous cancer, and the outcome of invasive thymoma, because there are various differences between the patients (Table 1). Ji Hyun Chang, MD Departments of Radiation Oncology and Cancer Research Institute Seoul National University College of Medicine Seoul, Republic of Korea
Hak Jae Kim, MD, PhD Hong-Gyun Wu, MD, PhD Departments of Radiation Oncology and Cancer Research Institute Seoul National University College of Medicine Seoul, Republic of Korea Institute of Radiation Medicine Medical Research Center Seoul National University Seoul, Republic of Korea
Joo Hyun Kim, MD, PhD Young Tae Kim, MD, PhD Department of Thoracic and Cardiovascular Surgery Seoul National University College of Medicine Seoul, Republic of Korea
REFERENCES 1. Chang JH, Kim HJ, Wu HG, et al. Postoperative radiotherapy for completely resected stage II or III thymoma. J Thorac Oncol 2011;6:1282–1286.
2. Venuta F, Rendina EA, Longo F, et al. Long-term outcome after multimodality treatment for stage III thymic tumors. Ann Thorac Surg 2003;76:1866 –1872; discussion 1872.
A Practical Guide to Measure “All” Malignant Pleural Mesothelioma Tumors by Modified RECIST Criteria? To the Editor: We read with interest the practical guidelines offered by Tsao et al.1 on how to make measurements of malignant pleural mesothelioma (MPM) by modified RECIST criteria. When we try to make a diagnosis of MPM, we usually rely on a combination of clinical characteristics, of radiological and (more recently also) nuclear imaging findings together with a confirmatory pleural biopsy and/or pleural cytology sample.2 Careful measuring of MPM tumor on computed tomography (CT) scan of the chest is crucial not only at initial diagnosis and staging but also for correct identification of tumor response to treatment. MPM may, however, present not only as a welldelineated and measurable pleural thickening but sometimes also as a much thinner, not really well-delineated rind-like pleural involvement. Occasionally, pleural involvement by MPM is only macroscopically detectable during thoracoscopy and later microscopically proven while the CT imaging does not show any significant pleural thickening at all. Differential diagnosis between minimal benign pleural thickening and MPM can indeed prove to be very challenging Disclosure: The authors declare no conflicts of interest. Address for correspondence: Kristiaan Nackaerts, MD, PhD, Department of Pulmonology/Respiratory Oncology, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium. E-mail: [email protected] Copyright © 2011 by the International Association for the Study of Lung Cancer ISSN: 1556-0864/11/0612-2143
Copyright © 2011 by the International Association for the Study of Lung Cancer
Letters to the Editor
based on CT scan only, and recently, the additional value of the fluorodeoxyglucose positron emission tomography imaging combined with CT scan has been demonstrated.2 What we actually missed in this practical guideline by Tsao et al. were the tips to “evaluate” MPM cases with these radiologically minimal rind-like thickenings or with occasional “nonmeasurable” or “normal” pleural MPM disease. When we participated in the landmark MPM trial by Vogelzang et al.,3 measurements of MPM pleural involvement were uniformly performed using the study protocol efficacy criteria for tumor response as modified from the preexisting Southwest Oncology Group standard tumor response criteria published by Green et al.4 Briefly, in patients with unidimensionally measurable disease, thickness of pleural rind had to be measured at three separate levels on transverse CT cuts. Levels should be at least 2 cm apart from each other. At each level, measurement of up to three areas of pleural rind should be performed where feasible. Measures should not be made of pleural thickening that was less than 1 cm. If bidimensionally measurable lesions coexisted, these could be measured according to RECIST criteria and the measurements could be added to the sum of the unidimensional measurements. In 2004, these adapted or modified RECIST guidelines on how to measure MPM tumors were published in detail by Byrne et al.5 According to the Vogelzang trial protocol, MPM disease status could be defined not only as measurable disease but sometimes also as “non-measurable” or “evaluable” disease and rarely as “nonevaluable” disease. Evaluable disease was defined as pleural lesions on CT scan with perpendicular diameters smaller than 1.0 cm, as has been also detailed in the practical guidelines by Tsao et al.1 In this category of evaluable or non-measurable rind-like pleural thickenings also pleural thickening secondary to previous talc pleurodesis may be classified. It is important, however, to document evaluable MPM disease at baseline and during treatment, because the evo-
2143
Letters to the Editor
lution of both measurable and evaluable disease needs to be taken into account for future response definition.4 This also holds partly true for nonevaluable MPM disease (like pleural effusion or ascites) because, for objective complete tumor response, nonevaluable MPM disease needs to be completely absent. In MPM patients with nonevaluable disease only where no complete response is present, no other MPM disease status can be assessed. As a suggestion, therefore, and in expectation of possible newer evaluation tools for MPM,2 we would like to propose the authors to provide clinicians with a complete practical guide on how to make radiologic measurements and evaluations of all possible MPM cases, presenting mostly with measurable, sometimes non-measurable, and occasionally with evaluable-only pleural disease. Kristiaan Nackaerts, MD, PhD Johan Vansteenkiste, MD, PhD Department of Pulmonology/Respiratory Oncology University Hospital Gasthuisberg Leuven, Belgium
Philippe Nafteux, MD Department of Thoracic Surgery University Hospital Gasthuisberg Leuven, Belgium
REFERENCES 1. Tsao AS, Garland L, Redman M, et al. A practical guide of the Southwest Oncology Group to measure malignant pleural mesothelioma tumors by RECIST and modified RECIST criteria. J Thoracic Oncol 2011;6: 598 – 601. 2. Nowak AK, Armato SG, Ceresoli GL, et al. Imaging in pleural mesothelioma: a review of imaging research presented at the 9th International Meeting of the International Mesothelioma Interest Group. Lung Cancer 2010;70:1– 6. 3. Vogelzang NJ, Rusthoven JJ, Symanowski J, et al. Phase III study of pemetrexed in combination with cisplatin versus cisplatin alone in patients with malignant pleural mesothelioma. J Clin Oncol 2003;21:2636 – 2644. 4. Green S, Weiss GR. Southwest Oncology Group standard response criteria, endpoint definitions and toxicity criteria. Invest New Drugs 1992;10:239 –253. 5. Byrne MJ, Nowak AK. Modified RECIST criteria for assessment of response in malignant pleural mesothelioma. Ann Oncol 2004; 15:257–260.
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Journal of Thoracic Oncology • Volume 6, Number 12, December 2011
Reply to the Letter to the Editor Entitled A Practical Guide to Measure “All” Malignant Pleural Mesothelioma Tumors by Modified RECIST Criteria? In Reply: We fully agree with Nackaerts et al. that there are significant radiographic challenges encountered when measuring thoracic mesothelioma tumors. As pointed out, mesothelioma is not always measurable by computed tomography (CT), magnetic resonance imaging, or positron emission tomography (PET) scans, and the classification of “nonmeasurable but evaluable” is a common conundrum. However, given our limitations with cost, technology availability, and consistency in radiographic measurements, the standard of care in cooperative group trials is to measure thoracic mesothelioma tumors with serial CT scans. Modified RECIST criteria by Byrne and Nowak1 is the preferred method of evaluating pleural tumors on CT scans as pleural disease measurements, using the short-axis rather than the long-axis diameter, appear to correlate better with clinical outcome. Given the rare incidence of mesothelioma and occasional confusion on how to measure pleural rinds, the intent of our recent publication2 was to serve as a practical guide (a step-bystep manual) to enhance consistency in disease measure-ments for the Southwest Oncology Group institutions. We concur with Nackaerts et al. that our current measurement practice is not optimal, and future studies of technology are vital to develop better and Disclosure: The authors declare no conflicts of interest. Address for correspondence: Anne S. Tsao, MD, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 432, Houston, TX 77030. E-mail: [email protected] Copyright © 2011 by the International Association for the Study of Lung Cancer ISSN: 1556-0864/11/0612-2144
more consistent measurements. In our recent publication, we did not intend to write a review on the different imaging modalities of measuring mesothelioma, which was clearly summarized in the recent publication by Nowak et al.3 The dilemma of measuring the “nonmeasurable but evaluable” mesothelioma tumors is that there is currently no technology that has been validated or consistently accurate. The labor-intensive strategy of area measurements rather than linear measurements would be impractical for a cooperative group to undertake, as not all investigators would have the resources, time, or expertise to conduct this study. While fluorodeoxyglucose PET and PET-CT scans are gaining popularity in imaging mesothelioma, and does show some promise, there are multiple factors that cause standardized uptake value measurements to vary from the initial baseline study to subsequent serial studies; and there is neither consensus nor validation of response criteria for mesothelioma. Some studies4 – 6 have previously reported a correlation to clinical outcome using either a metabolic response by measuring maximum standardized uptake values or total glycolytic volume; however, these trials are small in number and other studies7,8 have reported conflicting results. It is clear that additional prospective trials with radiographic correlates are needed to validate and develop new strategies based on our current technical capabilities; we hope that future research, perhaps new novel PET tracers, will overcome the complexity of measuring this nonspherical tumor. Anne S. Tsao, MD The University of Texas M. D. Anderson Cancer Center Houston, Texas
Linda Garland, MD Arizona Cancer Center University of Arizona Tucson, Arizona
Mary Redman, PhD Southwest Oncology Group Statistical Center Seattle, Washington
Kemp Kernstine, MD, PhD City of Hope National Medical Center and Beckman Research Institute Duarte, California
Copyright © 2011 by the International Association for the Study of Lung Cancer
this study, but we decided to leave them out to enhance the reliability of the results. As mentioned in the article, this study is a retrospective study, due to which it has limitations.1 We tried to improve the data homogeneity, however, by applying strict inclusion criteria as much as we could to overcome the effect of differences in the treatments between the past and the present. The main topic of our article was the necessity of adjuvant radiation therapy in the completely resected invasive thymoma, including stages II and III thymoma. Furthermore, unlike in the study of Venuta et al, we did not cover thymic carcinoma and incompletely resected tumors in the study.2 It would be difficult to compare our article with the article on the results of the study by Venuta et al. because the characteristics of the tumor are very different. It is well known that in an inoperable thymoma or thymic carcinoma, chemotherapy might be needed in the neoadjuvant/adjuvant setting. However, both were not the objects of this study. Therefore, it was not important to mention chemotherapy. Moreover, it is difficult to tell the relationship between chemotherapy and its absence after metachronous cancer, and the outcome of invasive thymoma, because there are various differences between the patients (Table 1). Ji Hyun Chang, MD Departments of Radiation Oncology and Cancer Research Institute Seoul National University College of Medicine Seoul, Republic of Korea
Hak Jae Kim, MD, PhD Hong-Gyun Wu, MD, PhD Departments of Radiation Oncology and Cancer Research Institute Seoul National University College of Medicine Seoul, Republic of Korea Institute of Radiation Medicine Medical Research Center Seoul National University Seoul, Republic of Korea
Joo Hyun Kim, MD, PhD Young Tae Kim, MD, PhD Department of Thoracic and Cardiovascular Surgery Seoul National University College of Medicine Seoul, Republic of Korea
REFERENCES 1. Chang JH, Kim HJ, Wu HG, et al. Postoperative radiotherapy for completely resected stage II or III thymoma. J Thorac Oncol 2011;6:1282–1286.
2. Venuta F, Rendina EA, Longo F, et al. Long-term outcome after multimodality treatment for stage III thymic tumors. Ann Thorac Surg 2003;76:1866 –1872; discussion 1872.
A Practical Guide to Measure “All” Malignant Pleural Mesothelioma Tumors by Modified RECIST Criteria? To the Editor: We read with interest the practical guidelines offered by Tsao et al.1 on how to make measurements of malignant pleural mesothelioma (MPM) by modified RECIST criteria. When we try to make a diagnosis of MPM, we usually rely on a combination of clinical characteristics, of radiological and (more recently also) nuclear imaging findings together with a confirmatory pleural biopsy and/or pleural cytology sample.2 Careful measuring of MPM tumor on computed tomography (CT) scan of the chest is crucial not only at initial diagnosis and staging but also for correct identification of tumor response to treatment. MPM may, however, present not only as a welldelineated and measurable pleural thickening but sometimes also as a much thinner, not really well-delineated rind-like pleural involvement. Occasionally, pleural involvement by MPM is only macroscopically detectable during thoracoscopy and later microscopically proven while the CT imaging does not show any significant pleural thickening at all. Differential diagnosis between minimal benign pleural thickening and MPM can indeed prove to be very challenging Disclosure: The authors declare no conflicts of interest. Address for correspondence: Kristiaan Nackaerts, MD, PhD, Department of Pulmonology/Respiratory Oncology, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium. E-mail: [email protected] Copyright © 2011 by the International Association for the Study of Lung Cancer ISSN: 1556-0864/11/0612-2143
Copyright © 2011 by the International Association for the Study of Lung Cancer
Letters to the Editor
based on CT scan only, and recently, the additional value of the fluorodeoxyglucose positron emission tomography imaging combined with CT scan has been demonstrated.2 What we actually missed in this practical guideline by Tsao et al. were the tips to “evaluate” MPM cases with these radiologically minimal rind-like thickenings or with occasional “nonmeasurable” or “normal” pleural MPM disease. When we participated in the landmark MPM trial by Vogelzang et al.,3 measurements of MPM pleural involvement were uniformly performed using the study protocol efficacy criteria for tumor response as modified from the preexisting Southwest Oncology Group standard tumor response criteria published by Green et al.4 Briefly, in patients with unidimensionally measurable disease, thickness of pleural rind had to be measured at three separate levels on transverse CT cuts. Levels should be at least 2 cm apart from each other. At each level, measurement of up to three areas of pleural rind should be performed where feasible. Measures should not be made of pleural thickening that was less than 1 cm. If bidimensionally measurable lesions coexisted, these could be measured according to RECIST criteria and the measurements could be added to the sum of the unidimensional measurements. In 2004, these adapted or modified RECIST guidelines on how to measure MPM tumors were published in detail by Byrne et al.5 According to the Vogelzang trial protocol, MPM disease status could be defined not only as measurable disease but sometimes also as “non-measurable” or “evaluable” disease and rarely as “nonevaluable” disease. Evaluable disease was defined as pleural lesions on CT scan with perpendicular diameters smaller than 1.0 cm, as has been also detailed in the practical guidelines by Tsao et al.1 In this category of evaluable or non-measurable rind-like pleural thickenings also pleural thickening secondary to previous talc pleurodesis may be classified. It is important, however, to document evaluable MPM disease at baseline and during treatment, because the evo-
2143
Letters to the Editor
lution of both measurable and evaluable disease needs to be taken into account for future response definition.4 This also holds partly true for nonevaluable MPM disease (like pleural effusion or ascites) because, for objective complete tumor response, nonevaluable MPM disease needs to be completely absent. In MPM patients with nonevaluable disease only where no complete response is present, no other MPM disease status can be assessed. As a suggestion, therefore, and in expectation of possible newer evaluation tools for MPM,2 we would like to propose the authors to provide clinicians with a complete practical guide on how to make radiologic measurements and evaluations of all possible MPM cases, presenting mostly with measurable, sometimes non-measurable, and occasionally with evaluable-only pleural disease. Kristiaan Nackaerts, MD, PhD Johan Vansteenkiste, MD, PhD Department of Pulmonology/Respiratory Oncology University Hospital Gasthuisberg Leuven, Belgium
Philippe Nafteux, MD Department of Thoracic Surgery University Hospital Gasthuisberg Leuven, Belgium
REFERENCES 1. Tsao AS, Garland L, Redman M, et al. A practical guide of the Southwest Oncology Group to measure malignant pleural mesothelioma tumors by RECIST and modified RECIST criteria. J Thoracic Oncol 2011;6: 598 – 601. 2. Nowak AK, Armato SG, Ceresoli GL, et al. Imaging in pleural mesothelioma: a review of imaging research presented at the 9th International Meeting of the International Mesothelioma Interest Group. Lung Cancer 2010;70:1– 6. 3. Vogelzang NJ, Rusthoven JJ, Symanowski J, et al. Phase III study of pemetrexed in combination with cisplatin versus cisplatin alone in patients with malignant pleural mesothelioma. J Clin Oncol 2003;21:2636 – 2644. 4. Green S, Weiss GR. Southwest Oncology Group standard response criteria, endpoint definitions and toxicity criteria. Invest New Drugs 1992;10:239 –253. 5. Byrne MJ, Nowak AK. Modified RECIST criteria for assessment of response in malignant pleural mesothelioma. Ann Oncol 2004; 15:257–260.
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Journal of Thoracic Oncology • Volume 6, Number 12, December 2011
Reply to the Letter to the Editor Entitled A Practical Guide to Measure “All” Malignant Pleural Mesothelioma Tumors by Modified RECIST Criteria? In Reply: We fully agree with Nackaerts et al. that there are significant radiographic challenges encountered when measuring thoracic mesothelioma tumors. As pointed out, mesothelioma is not always measurable by computed tomography (CT), magnetic resonance imaging, or positron emission tomography (PET) scans, and the classification of “nonmeasurable but evaluable” is a common conundrum. However, given our limitations with cost, technology availability, and consistency in radiographic measurements, the standard of care in cooperative group trials is to measure thoracic mesothelioma tumors with serial CT scans. Modified RECIST criteria by Byrne and Nowak1 is the preferred method of evaluating pleural tumors on CT scans as pleural disease measurements, using the short-axis rather than the long-axis diameter, appear to correlate better with clinical outcome. Given the rare incidence of mesothelioma and occasional confusion on how to measure pleural rinds, the intent of our recent publication2 was to serve as a practical guide (a step-bystep manual) to enhance consistency in disease measure-ments for the Southwest Oncology Group institutions. We concur with Nackaerts et al. that our current measurement practice is not optimal, and future studies of technology are vital to develop better and Disclosure: The authors declare no conflicts of interest. Address for correspondence: Anne S. Tsao, MD, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 432, Houston, TX 77030. E-mail: [email protected] Copyright © 2011 by the International Association for the Study of Lung Cancer ISSN: 1556-0864/11/0612-2144
more consistent measurements. In our recent publication, we did not intend to write a review on the different imaging modalities of measuring mesothelioma, which was clearly summarized in the recent publication by Nowak et al.3 The dilemma of measuring the “nonmeasurable but evaluable” mesothelioma tumors is that there is currently no technology that has been validated or consistently accurate. The labor-intensive strategy of area measurements rather than linear measurements would be impractical for a cooperative group to undertake, as not all investigators would have the resources, time, or expertise to conduct this study. While fluorodeoxyglucose PET and PET-CT scans are gaining popularity in imaging mesothelioma, and does show some promise, there are multiple factors that cause standardized uptake value measurements to vary from the initial baseline study to subsequent serial studies; and there is neither consensus nor validation of response criteria for mesothelioma. Some studies4 – 6 have previously reported a correlation to clinical outcome using either a metabolic response by measuring maximum standardized uptake values or total glycolytic volume; however, these trials are small in number and other studies7,8 have reported conflicting results. It is clear that additional prospective trials with radiographic correlates are needed to validate and develop new strategies based on our current technical capabilities; we hope that future research, perhaps new novel PET tracers, will overcome the complexity of measuring this nonspherical tumor. Anne S. Tsao, MD The University of Texas M. D. Anderson Cancer Center Houston, Texas
Linda Garland, MD Arizona Cancer Center University of Arizona Tucson, Arizona
Mary Redman, PhD Southwest Oncology Group Statistical Center Seattle, Washington
Kemp Kernstine, MD, PhD City of Hope National Medical Center and Beckman Research Institute Duarte, California
Copyright © 2011 by the International Association for the Study of Lung Cancer