Differences in Pleural Fluid Amylase Levels in Patients with Malignant Pleural Effusion Based on Cancer Type, Histologic Type, and Epidermal Growth Factor Receptor Mutations

Our plain-English summary of Differences in Pleural Fluid Amylase Levels in Patients with Malignant Pleural Effusion Based on Cancer Type, Histologic Type, and Epidermal Growth Factor Receptor Mutations, by M. Shimoda, Y. Tanaka, K. Morimoto, et al (Internal Medicine, 2023).

The study

• Authors: M. Shimoda, Y. Tanaka, K. Morimoto, K. Yoshimori, K. Ohta
• Journal: Internal Medicine
• Published: 2023;62(24):3601-3607
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective High pleural amylase levels have been reported in patients with malignant pleural effusion; however, the characteristics of this association are uncertain. Therefore, this study investigated the factors, such as cancer type and oncogenic drivers, related to pleural amylase levels in patients with malignant pleural effusion. Methods We retrospectively collected the data of 362 cancer patients [lung adenocarcinoma (n=256), lung squamous carcinoma (n=12), small-cell lung carcinoma (n=32), other lung cancers (n=5), mesothelioma (n=31), and metastatic cancer (n=26)] with malignant pleural effusion at Fukujuji Hospital from January 2012 to October 2022. Pleural amylase levels were compared. Results Pleural amylase levels were significantly higher in patients with lung adenocarcinoma [median 58.6 IU/L (interquartile range (IQR) 33.8-139.3)] than in those with small-cell lung carcinoma [median 37.2 IU/L (IQR 26.3-63.7), p=0.012]. The median pleural amylase level was higher in patients with lung adenocarcinoma than in those with other cancer or histologic types, although the difference was not significant. Pleural amylase levels were higher in epidermal growth factor receptor (EGFR) mutation-positive patients than in EGFR mutation-negative patients [median 95.8 IU/L (IQR 52.7-246.5) vs. median 51.2 IU/L (IQR 27.8-96.9), p<0.001]. The Kaplan-Meier survival curves of pleural amylase ≥75 IU/L were higher than those of pleural amylase <75 IU/L [log-rank test p<0.001, hazard ratio 0.54 (95% confidence interval: 0.41-0.71)]. Conclusion This study demonstrates that pleural amylase levels were elevated in patients with lung adenocarcinoma and EGFR mutations. Furthermore, a high pleural amylase level was associated with a good prognosis.

In plain English

This retrospective study reviewed records of 362 patients diagnosed with malignant pleural effusion at Fukujuji Hospital in Japan between January 2012 and October 2022. In each case, cancer cells had been found either in a sample of the fluid around the lungs or in a pleural biopsy. Most had lung adenocarcinoma (256 patients), and 31 had mesothelioma. The article does not report examining asbestos exposure. The authors compared levels of the enzyme amylase in the pleural fluid. The median level was significantly higher in lung adenocarcinoma (58.6 IU/L) than in small-cell lung carcinoma (37.2 IU/L). The mesothelioma group's median (41.1 IU/L) was lower than the adenocarcinoma group's, but the difference was not statistically significant. Patients with EGFR gene mutations had higher levels than those without (median 95.8 versus 51.2 IU/L). Patients with levels of 75 IU/L or more had a median survival of 384 days (95% confidence interval 245 to 523). Those below 75 IU/L had a median survival of 154 days (95% confidence interval 112 to 205). The authors concluded that a high level might be associated with a good prognosis. They noted that the study used one hospital's past records and did not take cancer treatments into account.

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 single-centre study of hospital records
• Who was studied: 362 patients with malignant pleural effusion at Fukujuji Hospital, Japan, January 2012 to October 2022, selected from 585 patients. Malignant pleural effusion was defined as malignant cells found in a pleural effusion sample or a pleural biopsy specimen. The patients had lung adenocarcinoma (256), lung squamous carcinoma (12), small-cell lung carcinoma (32), other lung cancers (5), mesothelioma (31) or metastatic cancer (26).
• Exposure: The article does not report any asbestos or fiber exposure assessment. The study compared pleural fluid amylase levels by cancer type, histologic type and gene mutations (EGFR, EML4-ALK), and related amylase levels to survival.
• Main results:
  • Pleural amylase was higher in lung adenocarcinoma (median 58.6 IU/L, IQR 33.8-139.3) than in small-cell lung carcinoma (median 37.2 IU/L, IQR 26.3-63.7), p=0.012.
  • Patients with mesothelioma (n=31) had a median pleural amylase of 41.1 IU/L (IQR 33.1-52.3). Compared with lung adenocarcinoma, the difference was not statistically significant (p=0.074).
  • EGFR mutation-positive patients (n=73) had higher pleural amylase (median 95.8 IU/L, IQR 52.7-246.5) than EGFR mutation-negative patients (n=136; median 51.2 IU/L, IQR 27.8-96.9), p<0.001.
  • EML4-ALK-positive patients (n=6) had higher pleural amylase (median 122.1 IU/L) than EML4-ALK-negative patients (n=100; median 51.8 IU/L), p=0.015.
  • Among all 362 patients, median overall survival was 384 days (95% CI 245-523) in the 125 patients with pleural amylase of 75 IU/L or more. It was 154 days (95% CI 112-205) in the 237 patients below 75 IU/L. The hazard ratio was 0.54 (95% CI 0.41-0.71), meaning a lower risk of death in the higher-amylase group.
  • In the multivariate analysis (Model I), the hazard ratio for mortality in the group with pleural amylase of 75 IU/L or more was 0.44 (95% CI 0.31-0.64). The other variables were not significant.
  • Among patients with major EGFR mutations (41 with pleural amylase of 75 IU/L or more and 25 below 75 IU/L), survival tended to be longer in the higher-amylase group (median 674 vs 364 days). The difference was not statistically significant (p=0.062, HR 0.57, 95% CI 0.31-1.04).
• The authors' conclusion: The authors concluded that pleural amylase levels tended to be higher in patients with lung adenocarcinoma and EGFR mutations than in others, and that a high pleural amylase level might be associated with a good prognosis.
• Limitations the authors state:
  • The study was retrospective and carried out at a single centre.
  • Treatments for the cancers were not considered in the mortality analysis.
  • Some patients, mainly those with metastatic cancer, were lost to follow-up after transferring to other hospitals.
  • EGFR and EML4-ALK mutations could not be measured in some patients, so EML4-ALK could not be included in the multivariate analysis.
  • The relationship between serum and pleural amylase could not be examined because few patients had serum amylase data.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Lung Adenocarcinoma, Carcinoma, Lung Cancer, Mesothelioma, EGFR, Hazard Ratio, confidence interval.

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