Clinical-pathological characteristics and prognostic factors for malignant peritoneal mesothelioma in the elderly

Our plain-English summary of Clinical-pathological characteristics and prognostic factors for malignant peritoneal mesothelioma in the elderly, by D. Pan, M. Wang, W. Liu, et al (BMC Gastroenterology, 2022).

The study

• Authors: D. Pan, M. Wang, W. Liu, Y. Li, L. Sang, B. Chang
• Journal: BMC Gastroenterology
• Published: 2022;22(1):292
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant peritoneal mesothelioma (MPM) is a rare disease characterized by atypical symptoms, difficult diagnosis, variable course and poor prognosis, and it develops mainly in elderly individuals. The authors aimed to identify the clinical-pathological characteristics, prognosis, and prognostic factors in elderly MPM patients.

Methods: From the National Cancer Institute Surveillance Epidemiology End Results (SEER) database, 1492 patients with MPM from 1975 to 2016 were selected and divided into the elderly group (≥ 65) and the adult group (< 65). We compared the clinical-pathological characteristics and treatment methods of the elderly group (N = 665) and the adult group (N = 827). At the same time, we analysed specific selected clinicopathological parameters and prognostic factors for elderly MPM patients.

Results: Compared with the adult group, the elderly group had higher percentages of male patients (P = 0.017) and white patients (P = 0.043) and lower proportions of insured patients (P < 0.001) married patients (P < 0.001), patients with peritoneal tumours (P = 0.006) and patients who underwent surgery (P < 0.001) and chemotherapy (P < 0.001). There was a significant difference in the differentiation grade between the two groups (P = 0.003). Elderly patients had a shorter median survival time than adult patients (6 months vs. 19 months). Uninsured (hazard ratio (HR): 5.187, P = 0.005), sarcomatoid type (HR 3.913, P < 0.001), poorly differentiated (HR 3.900, P < 0.001), distant metastasis (HR 1.735, P = 0.001), no cancer-directed surgery (HR 1.733, P < 0.001), and no chemotherapy (HR 1.532, P < 0.001) were independently associated with poorer prognosis in elderly MPM patients.

Conclusion: Compared with adult patients, elderly MPM patients had a higher male ratio, poor differentiation and relatively conservative treatment. The cancer-specific survival (CSS) rate of elderly MPM patients was significantly lower than that of adult patients. Insurance status, histology type, differentiation grade, stage, surgery status, and chemotherapy status were all independent prognostic factors for elderly MPM patients.

© 2022. The Author(s).

In plain English

This study used US SEER cancer registry records on 1,492 people with malignant peritoneal mesothelioma diagnosed from 1975 to 2016. It compared 665 patients aged 65 or older with 827 younger patients. It did not examine asbestos or any other exposure. The older group had more men (58.80% vs 52.60%) and less often had surgery (33.38% vs 47.88%) or chemotherapy (44.21% vs 59.7%). Median survival was 6 months for older and 19 months for younger patients, and five-year cancer-specific survival was 12.53% and 29.30%. Among older patients, worse survival was independently associated with being uninsured (only 3 such patients), sarcomatoid or biphasic tumours, poorly differentiated tumours, distant spread, no cancer-directed surgery, and no or unknown chemotherapy. Among older patients, radiotherapy showed no statistically significant link with survival (P = 0.173). However, only 15 had radiotherapy, and the comparison group mixed untreated patients with those of unknown status. The authors noted that tumour type and grade were unknown for most patients. They also noted that the registry does not separate patients who had no chemotherapy or radiotherapy from those whose status is unknown.

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 case series analysis of a US population cancer registry (SEER), comparing older and younger patients and using survival analysis (Kaplan-Meier and Cox regression)
• Who was studied: 1,492 patients with pathologically confirmed malignant peritoneal mesothelioma (including retroperitoneal sites) recorded in the US SEER registry from 1975 to 2016. 665 were aged 65 or older (the 'elderly group') and 827 were under 65 (the 'adult group'). Patients with other cancers or no active follow-up were excluded.
• Exposure: No asbestos or other exposure was studied; asbestos is mentioned only as background in the introduction and discussion. The study compared patients by age (65 and over vs under 65). It also examined sex, race, marital and insurance status, tumour site, histology type, grade, stage, and treatment (surgery, radiotherapy, chemotherapy).
• Main results:
  • Median survival was 6 months for patients aged 65 or older vs 19 months for those under 65. Five-year cancer-specific survival was 12.53% vs 29.30% (Table 3).
  • Compared with younger patients, the older group had a higher proportion of men (58.80% vs 52.60%, P = 0.017).
  • Compared with younger patients, older patients less often had surgery (33.38% vs 47.88%) and chemotherapy (44.21% vs 59.7%), both P less than 0.001.
  • Among older patients in the multivariate analysis, uninsured patients had a higher risk of cancer-specific death than insured patients: HR 5.187 (95% CI 1.628 to 16.524), P = 0.005. Only 3 older patients were recorded as uninsured, and all 3 died. Insurance status was unknown for 423 of the 665 older patients.
  • Among older patients, compared with epithelioid tumours, the risk of cancer-specific death was higher for sarcomatoid tumours (HR 3.913, 95% CI 2.347 to 6.523, P less than 0.001). It was also higher for biphasic tumours (HR 2.279, 95% CI 1.339 to 3.877, P = 0.002).
  • Among older patients, compared with well-differentiated tumours, the risk was higher for poorly differentiated tumours (HR 3.900, 95% CI 2.194 to 6.933, P less than 0.001) and for undifferentiated tumours (HR 2.430, 95% CI 1.038 to 5.689, P = 0.041). The result for moderately differentiated tumours (HR 1.978, 95% CI 0.811 to 4.824, P = 0.134) was not statistically significant.
  • Among older patients, distant metastasis carried a higher risk than localized disease: HR 1.735 (95% CI 1.255 to 2.401), P = 0.001.
  • Among older patients, those without cancer-directed surgery had a higher risk of cancer-specific death than those who had it: HR 1.733 (95% CI 1.433 to 2.095). Five-year cancer-specific survival was 19.14% with surgery vs 8.76% without.
  • Among older patients, those with no or unknown chemotherapy had a higher risk than those who had chemotherapy: HR 1.532 (95% CI 1.282 to 1.831), P less than 0.001.
  • Among older patients, median survival was 9 months for women and 5 months for men. Five-year cancer-specific survival was 14.79% for women and 10.88% for men.
  • Among older patients, no statistically significant association with cancer-specific survival was found for radiotherapy status (P = 0.173), race (P = 0.507) or tumour site (P = 0.936). Only 15 older patients were recorded as receiving radiotherapy. The comparison group combined patients with no radiotherapy and those whose status was unknown.
• The authors' conclusion: The authors concluded that, for older patients with malignant peritoneal mesothelioma, being insured, having an epithelioid tumour and having a well-differentiated tumour were favourable prognostic factors. They concluded that distant metastasis and no surgery or chemotherapy were independently associated with poorer prognosis. They added that all risk factors and each patient's specific conditions should be assessed when choosing treatment.
• Limitations the authors state:
  • The SEER database does not separate patients who did not receive chemotherapy or radiotherapy from those whose status for these treatments is unknown. The authors said this means the effect of these two treatments cannot be judged precisely.
  • SEER has no information on specific chemotherapy regimens, so the effects of different regimens could not be studied.
  • Histology type and differentiation grade were unknown for most patients, which the authors said affected the accuracy of the results.
  • SEER collects data from only 18 US regions, which the authors said places regional limitations on the results.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma, Peritoneal mesothelioma.

Medical terms in this study, explained in our Lexicon: Peritoneal Mesothelioma, Prognosis, Epidemiology, SEER, Chemotherapy, Median Overall Survival, Hazard Ratio, Sarcomatoid.

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