Paradoxical Improvement in Malignant Pleural Mesothelioma Outcomes Following Delayed Treatment Initiation

Our plain-English summary of Paradoxical Improvement in Malignant Pleural Mesothelioma Outcomes Following Delayed Treatment Initiation, by A. Kulshrestha, E. Taioli, A. Wolf, et al (Cancers, 2024).

The study

• Authors: A. Kulshrestha, E. Taioli, A. Wolf, R. Flores, S. Tuminello
• Journal: Cancers
• Published: 2024;16(22)
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background/objectives: Time to treatment initiation (TTI) has been identified as a predictor of survival in many cancers, but its impact on malignant pleural mesothelioma (MPM) is unknown. This study investigates factors influencing TTI in MPM and its association with overall survival.

Methods: The Surveillance, Epidemiology, and End Results (SEER) database was used to obtain data for MPM patients in the United States. TTI was defined as the number of days from diagnosis to initiation of first treatment, and delayed TTI was defined as exceeding the median TTI. Χ2 tests and t-tests compared sociodemographic and clinical differences between early and delayed TTI groups, while Kaplan-Meier and Cox proportional hazards models evaluated relationships between prognostic factors, TTI, and survival.

Results: Among 4879 MPM patients, the median TTI was 39 days. Median survival was 10 months among early TTI patients and 13 months among delayed TTI patients. Patients with epithelioid histology were more likely to have delayed TTI, as were patients who received combination therapy or were diagnosed more recently (p < 0.0001). Adjusting for covariates, delayed TTI status remained associated with better survival (HR 0.79, 95% CI: 0.74-0.84).

Conclusions: This study presents an important insight into the management of MPM, demonstrating that delayed time to treatment initiation is positively associated with improved overall survival, contrary to findings in most cancers. This finding underscores the importance of comprehensive, multidisciplinary care, as delays due to robust staging evaluations and patient travel to high-volume centers of excellence likely contribute to delays in treatment. Taken together, these results suggest that clinicians should prioritize personalized treatment planning and collaborative care over a push to rapidly initiate treatment to optimize patient outcomes in MPM.

In plain English

This study used the US Surveillance, Epidemiology, and End Results (SEER) cancer database to ask whether the time between diagnosis and the start of treatment was linked to survival in malignant pleural mesothelioma. The authors analyzed 4879 treated patients with pathologically proven pleural mesothelioma diagnosed from 2004 onward. The median wait was 39 days, and patients who waited longer than that were classed as 'delayed'. Median survival was 10 months in the early group and 13 months in the delayed group. After adjusting for factors including age, sex, race, stage, histology and treatment, a delayed start remained associated with a lower risk of death (hazard ratio 0.79, 95% CI 0.74 to 0.84). Delayed patients were more likely to have epithelioid tumors. The association held in subgroups treated with surgery alone, with epithelioid histology, and with localized or regional disease. The authors suggested, without testing it, that thorough staging and travel to specialist centers might explain the finding. They noted that SEER lacks comorbidity and fitness data and reports treatment unreliably. Asbestos exposure was not studied.

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 analysis of a US national cancer registry database (SEER), comparing early and delayed treatment start using survival curves and Cox proportional hazards models
• Who was studied: 4879 patients in SEER registries (United States) with pathologically proven mesothelioma of the pleura, diagnosed from 2004 onward, known to have received treatment, with a time to treatment of 1 to 365 days. Autopsy cases and other sites (peritoneum, pericardium, etc.) were excluded.
• Exposure: Not asbestos. The exposure studied was time to treatment initiation (days from diagnosis to first treatment), with 'delayed' defined as longer than the median.
• Main results:
  • Median time to treatment initiation was 39 days among the 4879 patients. 2428 were in the early group and 2451 in the delayed group.
  • Median overall survival was 10 months in the early TTI group and 13 months in the delayed TTI group (p less than 0.0001).
  • After adjustment for covariates, delayed TTI was associated with better survival compared to early TTI (adjusted HR 0.79, 95% CI 0.74–0.84).
  • Delayed TTI patients were more likely to have epithelioid histology (p less than 0.0001).
  • The early and delayed groups did not differ significantly in age, sex, race, practice setting, income or marital status.
  • Among 392 patients treated with surgery alone, median overall survival was 4 months in the early TTI group and 11 months in the delayed TTI group (p = 0.0003; median TTI 34.5 days).
  • Among surgery-only patients, delayed TTI was associated with improved survival after adjustment (adjusted HR 0.67, 95% CI 0.54–0.84).
  • Among patients with epithelioid histology, delayed TTI remained associated with better survival after adjustment (adjusted HR 0.87, 95% CI 0.79–0.95).
  • Among patients with locoregional disease, delayed TTI was associated with improved survival (adjusted HR 0.83, 95% CI 0.74–0.93).
  • In the whole cohort, male patients (adjusted HR 1.19, 95% CI 1.10–1.28) and Black patients compared to White patients (adjusted HR 1.12, 95% CI 1.03–1.22) had poorer survival.
  • Combination therapy was associated with better overall survival than surgery alone (adjusted HR 0.62, 95% CI 0.54–0.70).
• The authors' conclusion: The authors concluded that although treatment should be started in a timely manner, a delay in starting it was not necessarily associated with poorer overall survival. They suggested that travel to mesothelioma centers of excellence and a proper workup should be encouraged.
• Limitations the authors state:
  • Treatment information in SEER is irregularly reported.
  • Treatment dates and sequence are not available, and it is unclear which treatment a patient received first.
  • Excluding patients with a time to treatment of 0 days may have introduced selection bias.
  • SEER lacks detailed comorbidity and patient fitness information, so unmeasured confounding could not be assessed.
  • It was not possible to assess which patients had access to specialized mesothelioma care or what workup was done before treatment.
  • Generalizability is limited because of sampling restrictions.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Overall Survival, Epidemiology, SEER, Median Overall Survival, Epithelioid, Histology, Multidisciplinary Team.

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