Retrospective analysis of unknown primary cancers with malignant pleural effusion at initial diagnosis

Our plain-English summary of Retrospective analysis of unknown primary cancers with malignant pleural effusion at initial diagnosis, by T. Ebata, Y. Okuma, Y. Nakahara, et al (Thoracic Cancer, 2016).

The study

• Authors: T. Ebata, Y. Okuma, Y. Nakahara, M. Yomota, Y. Takagi, Y. Hosomi, E. Asami, Y. Omuro, T. Hishima, T. Okamura, Y. Takiguchi
• Journal: Thoracic Cancer
• Published: 2016;7(1):39-43
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant pleural effusion (MPE) can occur during the progression of various cancers. However, factors, such as the incidence of MPE associated with different types of cancers and its potential for diagnosing previously undetected cancers, are unknown. Moreover, MPE may accompany potentially curable cancers or those with a favorable survival prognosis with adequate treatment. The present study determined the types of cancers accompanied by MPE at initial diagnosis and investigated appropriate related methods for diagnosing previously unknown cancers.

Methods: We retrospectively reviewed the medical records of 35 patients with MPE at initial cancer diagnosis between 2004 and 2012. We evaluated the patient characteristics, final diagnosis, and diagnostic processes.

Results: Of the 35 patients, 10 had lung cancer, seven ovarian or peritoneal cancer, four malignant pleural mesothelioma, one breast cancer, one lymphoma, one pancreatic cancer, and 11 had cancers of unknown origin. Diagnoses of the primary lesions were confirmed using the MPE cellblock method for seven of 11 patients (63.6%), by excisional biopsy or aspiration from other sites in four of nine patients, by exploratory laparotomy in two of three patients, and by peritoneal washing cytology in five patients.

Conclusion: Lung cancer and cancer of unknown origin are major causes of MPE at initial presentation. However, these groups also contain cancers that are curable and those with good long-term prognosis. The MPE cellblock method represents an accurate method for identifying cancer origin.

In plain English

The authors reviewed records of 35 patients at a Tokyo cancer hospital whose cancer was first found through malignant pleural effusion (cancer cells in the fluid around the lungs) between July 2004 and July 2012. The study did not examine asbestos or any other exposure. Ten patients had lung cancer, seven ovarian or peritoneal cancer, four malignant pleural mesothelioma, one each lymphoma, breast cancer and pancreatic cancer, and 11 cancer of unknown primary origin. A laboratory technique for testing the fluid, the cellblock method, identified the cancer's origin in seven of 11 patients tested, including three with mesothelioma. Biopsy or aspiration of other sites identified it in four of nine patients. Exploratory abdominal surgery (laparotomy) found ovarian cancer in two of three women. Some patients were first wrongly diagnosed with adenocarcinoma from fluid cytology before being diagnosed with mesothelioma or reactive mesothelial cells. The authors concluded that although such effusions may tend to come from cancers with a poor prognosis, they can also point to potentially curable cancers. The authors named as limitations the retrospective design, the small number of patients, and that not all patients received the same tests.

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 review of hospital medical records
• Who was studied: 35 patients (20 men, 15 women; median age 67, range 44 to 93) whose cancer was first diagnosed through malignant pleural effusion at Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, Japan, July 2004 to July 2012. Patients histologically diagnosed with a cancer in the previous five years were excluded.
• Exposure: Not studied; the article does not report asbestos or any other exposure.
• Main results:
  • Final diagnoses among the 35 patients: lung cancer 10 (28.6%), ovarian or peritoneal cancer 7 (20%), malignant pleural mesothelioma 4 (11.4%), one each (3%) lymphoma, breast cancer and pancreatic cancer, and cancer of unknown primary origin 11 (31.4%).
  • The cellblock method applied to pleural fluid identified the primary cancer in 7 of 11 patients tested (63.6%): three malignant pleural mesothelioma, two lung cancer, one lymphoma and one breast cancer.
  • Excisional biopsy or aspiration of lymph nodes or other sites, done in 9 patients, identified the primary site in 4 (44.4%): two lung, one pancreatic and one peritoneal cancer.
  • Three women with peritoneal effusion underwent exploratory laparotomy; two were diagnosed with ovarian cancer.
  • Cytology of the pleural fluid showed adenocarcinoma in 27 of 35 patients (77%) and mesothelial cells in two (6%).
  • Some patients were first incorrectly diagnosed with adenocarcinoma by cytology before being diagnosed with malignant pleural mesothelioma or reactive mesothelial cells.
  • 13 of 35 patients (37%) had only pleural lesions, with no other metastatic site.
• The authors' conclusion: The authors concluded that although malignant pleural effusion may tend to come from cancers with a poor prognosis, it can also be used to identify potentially curable cancers in patients who may survive long-term, and so may help guide treatment.
• Limitations the authors state:
  • Retrospective design and a small number of patients.
  • Patients did not all undergo the same diagnostic procedures, which individual physicians decided.
  • Agreement between histological biopsy and the cellblock method was not confirmed, so the authors could not say which method was more useful.
  • Patients with cancer of unknown origin included those in poor condition who received supportive care only and had less invasive examinations.
  • The sensitivity of the cellblock method in this study was lower than in earlier studies, which the authors attributed possibly to patient selection. They stated that further studies are needed to confirm its role.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Prognosis, Lung Cancer, Pleural Mesothelioma, Biopsy, Laparotomy, Cytology.

Related studies

• Evaluation of pleural fluid cytology for the diagnosis of malignant pleural effusion: a retrospective cohort study — L. Pairman, L.E.L. Beckert, et al. (2022)
• Poorly differentiated neoplasms of unknown primary site: diagnostic usefulness of a molecular cancer classifier assay — F.A. Greco, W.J. Lennington, et al. (2015)
• Integrated Histogenetic Analysis Reveals BAP1-Mutated Epithelioid Mesothelioma in a Patient With Cancer of Unknown Primary — T. Bochtler, V. Endris, et al. (2018)
• Cardiac tamponade as the initial manifestation of primary pericardial mesothelioma — M. Stein, A. Neuman, et al. (1995)
• A Case Report of Pericardial Effusion with False-Positive Mesothelioma and Adenocarcinoma Markers as the Initial Presentation of Systemic Lupus Erythematous — G. Bhattacharya, P.P. Gupta (2022)
• Diagnosis and initial management of nonmalignant diseases related to asbestos — American Thoracic Society (2004)

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