Outcome of dogs treated with chemotherapy for mesothelioma: A retrospective clinical study on 40 cases and a literature review

Our plain-English summary of Outcome of dogs treated with chemotherapy for mesothelioma: A retrospective clinical study on 40 cases and a literature review, by M. Lajoinie, T. Chavalle, F. Floch, et al (Veterinary and Comparative Oncology, 2022).

The study

• Authors: M. Lajoinie, T. Chavalle, F. Floch, D. Sayag, D. Lanore, F. Ponce, G. Chamel
• Journal: Veterinary and Comparative Oncology
• Published: 2022;20(4):825-835
• Type of article: Review
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Mesothelioma is an uncommon cancer in dogs for which there is no established standard of care. Chemotherapy is often suggested despite no definitive proof of efficacy. The aim of this study was to evaluate the impact of chemotherapy on survival of dogs with mesothelioma. A retrospective multicentric study was carried out. To be included, dogs needed to present an evocative clinical evolution and a morphological diagnosis of mesothelioma. Exclusion of other cause of effusion and complete clinical follow-up were also required. Fourty dogs were included, 27 received chemotherapy (group 1) and 13 did not (group 2). Groups were heterogeneous regarding the proportion of animals undergoing surgery as part of their treatment (16 in group 1, 2 in group 2; p = .016) and homogeneous otherwise. Univariate analysis showed that dogs from group 1 survived significantly longer than dogs from group 2 (MST: 366 vs. 74 days; p < .001). Complete resolution of effusion after the first chemotherapy administration positively correlated with survival in group 1 (MST: 415 vs. 160 days; p < .01). All other variable tested had no significant impact on survival in univariate analysis, but dogs undergoing surgery and dogs having serous membranes' modification at medical imaging tended to survive longer. Multivariate analysis confirmed that chemotherapy was the sole variable independently associated with survival in our study (odds ratio 5.57-6.12; p < .01).

© 2022 The Authors. Veterinary and Comparative Oncology published by John Wiley & Sons Ltd.

In plain English

This article reported a retrospective study of 40 dogs diagnosed with mesothelioma from 2004 to 2020 at six veterinary institutions, plus a review of published dog cases. It did not study asbestos. Twenty-seven dogs received chemotherapy, mostly cisplatin or carboplatin placed into the affected body cavity; 13 did not. Median survival was 366 days with chemotherapy and 74 days without it (p less than 0.001). In two adjusted analyses, chemotherapy was the only factor that remained associated with survival. Surgery was more common with chemotherapy (16 of 27 dogs) than without (2 of 13). Dogs that had surgery tended to live longer, but this was not statistically significant. Among chemotherapy-treated dogs, 13 of 26 had a complete response three weeks after the first dose. This meant the tumour-related fluid had disappeared on ultrasound and no new fluid had appeared. These dogs survived a median 415 days, against 160 for the others (p less than 0.01). The authors concluded that chemotherapy was associated with longer survival in their cohort; the effect of surgery remains unknown. They noted the retrospective design, non-standardized protocols and small numbers as limitations.

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 multicentre clinical study (veterinary), combined with a review of previously published canine mesothelioma cases (122 cases from 47 case reports and 10 case series)
• Who was studied: 40 dogs with mesothelioma, diagnosed January 2004 to April 2020 at six veterinary institutions. It was pleural in 15, pericardial in 12, peritoneal in 2, and involved more than one body cavity in the rest.
• Exposure: The exposure studied was treatment with chemotherapy, not asbestos. 27 dogs received chemotherapy (group 1) and 13 did not (group 2). Chemotherapy into the body cavity used cisplatin or carboplatin. Intravenous agents included carboplatin, doxorubicin and others.
• Main results:
  • Median survival was 366 days for dogs treated with chemotherapy (group 1) and 74 days for dogs not given chemotherapy (group 2), p less than .001.
  • In two separate multivariate (Cox) analyses, only chemotherapy remained significantly associated with survival. Table 3 gives hazard ratios for group 2 versus group 1 of 5.57 [1.96; 15.8] when adjusted for surgery and 6.12 [2.31; 16.2] when adjusted for imaging abnormalities.
  • A significantly higher percentage of dogs in the chemotherapy group underwent surgery than in the group not given chemotherapy: 16 of 27 dogs versus 2 of 13.
  • Across all 40 dogs, those having surgery tended to live longer (median 366 vs. 151 days), but this was not statistically significant.
  • Of 26 chemotherapy-treated dogs with reported response, 13 (50%) had a complete response 3 weeks after the first chemotherapy dose. Complete response was defined as disappearance of previously diagnosed neoplastic effusion and no newly diagnosed effusion.
  • Among chemotherapy-treated dogs, complete responders had a median survival of 415 days versus 160 days for incomplete responders (p less than .01).
  • In dogs with pleural mesothelioma only, chemotherapy was significantly associated with survival (median 214 vs. 40 days).
  • In dogs with pericardial mesothelioma only, those treated with chemotherapy tended to live longer (median 366 vs. 102 days), but this was not statistically significant.
  • Four adverse events were recorded among chemotherapy-treated dogs. No renal toxicity was reported.
• The authors' conclusion: The authors concluded that chemotherapy was associated with increased survival of dogs with mesothelioma in their cohort. Complete response after the first dose was the only positive prognostic factor they identified, and the impact of surgery on survival remains unknown.
• Limitations the authors state:
  • The study was retrospective.
  • Diagnostic, staging and treatment protocols were not standardized.
  • Multivariate analyses could not always be performed because of the small number of cases.
  • Only two dogs in the group not given chemotherapy had surgery, too few to assess whether surgery is effective.
  • Complete staging was not performed in all dogs.

Topics

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

Medical terms in this study, explained in our Lexicon: Chemotherapy, Mesothelioma, Multivariate Analysis, Odds Ratio.

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