Main Session

Sep 28

PQA 03 - Digital Health Innovation and Informatics, Patient Safety & Quality, and Radiation and Cancer Biology

2453 - The Role of PJP Prophylaxis for Individuals Undergoing Chemo-Radiotherapy for the Treatment of Glioblastoma

10:45am - 12:00pm ET

Poster Hall - Exhibit Hall A

Screen: 32

POSTER

Presenter(s)

Ariel Feather, MD, BS - McMaster University, Hamilton, ON

A. Y. Feather¹, R. Ramos^2,3, N. Kalidindi^2,3, C. Hann⁴, A. C. Whitton^3,4, J. N. Greenspoon^3,4, and C. A. Beers^3,4; ¹McMaster University, Hamilton, ON, Canada, ²McMaster University, Division of Neurology, Hamilton, ON, Canada, ³Juravinski Cancer Centre, Hamilton, ON, Canada, ⁴McMaster University, Department of Oncology, Hamilton, ON, Canada

Purpose/Objective(s):

In glioblastoma (GBM), glucocorticoid treatment while undergoing chemo-radiotherapy is a mainstay to help manage CNS radiation side effects. Established indications for prophylactic trimethoprim-sulfamethoxazole (TMP-SMX) treatment for pneumocystis jirovecii pneumonia (PJP) include individuals treated with a glucocorticoid dose equivalent to =20 mg of prednisone daily for one month or longer. PJP prophylaxis is not routinely used at the Juravinski Cancer Centre (JCC) in these patients. With this project, we sought to interrogate the incidence of PJP and associated risk factors in recently treated individuals diagnosed with GBM at the JCC.

Materials/Methods:

Using the EMR EPIC, file review was performed for all individuals diagnosed and treated for GBM between March and November 2024 at the JCC. Eligibility criteria included age under 70 and completed 6 weeks of radiation combined with temozolomide (TMZ) chemotherapy (cohort 1) or age over 70 treated with 3 weeks of radiation combined with TMZ (cohort 2), received doses of =4mg of dexamethasone (prednisone equivalent >20mg) during treatment, and survived for at least three months post chemoradiotherapy. To assess the incidence of PJP, each case was reviewed for chest imaging, antibiotic usage, microbiological testing, and hospital admissions. In patients diagnosed with all types of pneumonia, CBC testing performed at the completion of radiotherapy was assessed and compared to age/sex matched controls also on treatment.

Results:

For cohort 1, 32 individuals met the inclusion criteria. Of these 32 cases, 7 received chest imaging within 90 days of completing chemoradiotherapy. Of these 7 cases, 5 were diagnosed with pneumonia, 1 of which was diagnosed as viral COVID-19 pneumonia. Of the 4 remaining cases, 3 were treated for community-acquired pneumonia, and 1 was diagnosed with PJP. Comparing the CBC values at the end of treatment for the 4 cases of pneumonia to age/sex-matched controls also on treatment, those who developed pneumonia demonstrated both lymphocyte values below 0.5 x 10^9/L and platelet levels below 150 x 10^9/L, which were not found in controls.

For cohort 2, 10 individuals met the inclusion criteria. Of these 10 cases, 3 received chest imaging within 90 days of completing treatment. Of these 3 cases, 1 was diagnosed with pneumonia felt to be related to an aspiration event and required antibiotic treatment. No cases were diagnosed with PJP. No signals from abnormal bloodwork were appreciated in this case when compared to age/sex-matched controls.

Conclusion:

Given the low number of PJP cases in this dataset and risk of thrombocytopenia from both prophylactic TMP-SMX and TMZ, it was felt that routine PJP prophylaxis is not warranted for this group of patients. However, from our CBC findings in cohort 1, lymphocyte and platelet values at the end of treatment may serve as a predictor of higher risk for the development of pneumonia in these individuals, and could help guide decision-making for the use of PJP prophylaxis.