Chemotherapy Versus Supportive Care for Unresected Malignant Pleural Mesothelioma

Quantitation and predictors of short-term mortality following extrapleural pneumonectomy, pleurectomy/decortication, and nonoperative management for malignant pleural mesothelioma

Background

For malignant pleural mesothelioma (MPM), the benefit of resection, as well as the optimal surgical technique, remain controversial. In efforts to better refine patient selection, this retrospective observational cohort study queried the National Cancer Database in an effort to quantify and evaluate predictors of 30- and 90-day mortality between extrapleural pneumonectomy (EPP) and pleurectomy/decortication (P/D), as well as nonoperative management.

Methods

After applying selection criteria, cumulative incidences of mortality by treatment paradigm were graphed for the unadjusted and propensity-matched populations, as well as for six a priori age-based intervals (≤60, 61–65, 66–70, 71–75, 76–80, and ≥81 years). The interaction between age and hazard ratio (HR) for mortality between treatment paradigms was also graphed. Cox multivariable analysis ascertained factors independently associated with 30- and 90-day mortality.

Results

Of 10,723 patients, 2,125 (19.8%) received resection (n=438 EPP, n=1,687 P/D) and 8,598 (80.2%) underwent nonoperative management. The unadjusted 30/90-day mortality for EPP, P/D, and all operated cases was 3.0%/8.0%, 5.4%/14.1%, and 4.9%/12.8%, respectively. There were no short-term mortality differences between EPP and P/D following propensity-matching, within each age interval, or between age subgroups on interaction testing (P>0.05 for all). Nonoperative patients had a crude 30- and 90-day mortality of 9.9% and 24.6%, respectively. Several variables were identified as predictors of short-term mortality, notably patient age (HR 1.022, P<0.001), Charlson-Deyo comorbidity index (HR 1.882, P<0.001), receipt of treatment at high-volume centers (HR 0.834, P=0.032) and induction chemotherapy (HR 1.735, P=0.025), among others. The patient (yearly) incremental increase in age conferred 2.0% (30 day) and 2.2% (90 day) increased risk of mortality (P<0.001).

Conclusions

Quantitative estimates of age-associated 30- and 90-day mortality of EPP and P/D should be considered when potentially operable patients are counseled regarding the risks and benefits of resection.

Racial Disparities in Treatment Patterns and Survival Among Surgically Treated Malignant Pleural Mesothelioma Patients

Surgery may improve survival in malignant pleural mesothelioma (MPM) patients. We examined treatment and survival in black and white surgical MPM patients using the National Cancer Database (NCDB). Among patients with pleurectomy/decortication (PD) or extrapleural pneumonectomy (EPP), multivariable logistic regressions were used to evaluate racial differences in surgical extent, additional treatment, and 30-/90-day mortality. Multivariable and propensity matched models were used to assess differences in survival. We identified 2550 patients; 2462 white (96.5%), 88 black (3.5%). Black patients were significantly less likely to receive EPP (OR_adj 0.36, 95% CI 0.17-0.78) and trended towards worse 30-/90-day mortality (OR_adj 1.54, 95% CI 0.59-4.03; OR_adj 1.59, 95% CI 0.80-3.17, respectively). There was no difference in survival (HR_adj 0.94, 95% CI 0.71-1.25). Surgery conferred a survival benefit (HR_adj 0.77, 95% CI 0.73-0.82), but it varied by race (HR_adj[white] 0.76, 95% CI 0.72-0.81; HR_adj[black] 0.93, 95% CI 0.67-1.29). With the limitation of a small proportion of surgically resected black MPM patients in this population-based analysis, black patients were noted to undergo less extensive surgery. Although there was an overall survival benefit noted with surgery, this was not consistent across races, despite trends towards worse short-term mortality in black patients.

Gender-based Disparities in Receipt of Care and Survival in Malignant Pleural Mesothelioma

BACKGROUND

Despite accounting for a minority of malignant pleural mesothelioma (MPM) diagnoses, females may experience differential survival relative to males. It is unclear if there are gender-based differences in receipt of treatment or disease-related outcomes for patients with MPM. We therefore utilized the National Cancer Database (NCDB) to assess patterns-of-care and overall survival (OS) among patients with MPM by gender.

MATERIALS AND METHODS

Patients with histologically confirmed MPM treated from 2004 to 2013 were identified from the NCDB. The association between female gender and OS was assessed using multivariable Cox proportional hazards models with propensity score matching. Patterns-of-care were assessed using multivariable logistic regression. The overall treatment effect was tested in subsets of patients by treatment strategy, histology, and clinical stage.

RESULTS

A total of 18,799 patients were identified, of whom 14,728 (78%) were male and 4071 (22%) were female. Females were statistically more likely to present at a younger age, with fewer comorbidities, and with epithelioid histology. Despite these favorable prognostic features, women were less likely to receive surgery (P ≤ .001) or chemotherapy (P ≤ .001) compared with males. On multivariable analysis, female gender was associated with improved OS (hazard ratio, 0.83; 95% confidence interval, 0.80-0.86; P ≤ .001). Gender-based survival differences were seen across all stages, but only among patients with epithelioid (P ≤ .001) and not biphasic (P = .17) or sarcomatoid (P = 1.00) histology.

CONCLUSIONS

Surgery and chemotherapy are disproportionately underutilized in female patients with MPM. Despite this concerning disparity, female gender is independently associated with improved survival relative to males. Further research to understand factors that lead to gender disparities in MPM is warranted.

Impact of Detecting Occult Pathologic Nodal Disease During Resection for Malignant Pleural Mesothelioma

BACKGROUND

Lymph node (LN) involvement is a poor prognostic factor for malignant pleural mesothelioma (MPM). However, to our knowledge, postresection outcomes of node-negative (cN0/pN0), occult pathologic nodal disease (cN0/pN+), and clinical node-positive disease (cN+) have not been compared to date.

PATIENTS AND METHODS

The National Cancer Data Base was queried for newly diagnosed, resected MPM with known clinical/pathologic LN information. Three cohorts were compared: cN0/pN0, cN+, and cN0/pN+. Multivariable logistic regression examined predictors of pathologic nodal upstaging. Kaplan-Meier analysis with propensity matching assessed overall survival (OS); multivariate Cox proportional hazards modeling examined predictors thereof.

RESULTS

Of 1369 patients, 687 (50%) had cN0/pN0, 457 (33%) cN+, and 225 (16%) cN0/pN+ disease. Median follow-up was 29 months. In patients with cN0 disease, factors associated with pathologic nodal upstaging were younger age, greater number of examined LNs, and nonsarcomatoid histology (P < .05 for all). Relative to pN0 cases, occult LN involvement (65% being pN2) was associated with 51% higher hazard of mortality on multivariate analysis (P = .005). Following propensity matching, the OS of cN0/pN+ was similar to cN+ cases (P = .281). On multivariate analysis, the number of involved LNs (continuous variable, P = .013), but not nodal tumor, node, metastasis (TNM) classification or LN ratio (P > .05 for both), was associated with OS.

CONCLUSION

Detecting occult nodal disease during resection for cN0 MPM is associated with poorer prognosis, with similar survival as cN+ cases, underscoring the importance of routine preoperative pathologic nodal assessment for potentially resectable MPM. The number of involved LNs (rather than current location-based classification) may provide more robust prognostic stratification for future TNM staging.