Introduction: Patients with hematological malignancies (HMs), like chronic lymphocytic leukemia (CLL), multiple myeloma (MM), and non-Hodgkin lymphoma (NHL), have a high risk of secondary immunodeficiency (SID), SID-related infections, and mortality. Here, we report the results of a systematic literature review on the potential association of various cancer regimens with infection rates, neutropenia, lymphocytopenia, or hypogammaglobulinemia, indicative of SID., Methods: A systematic literature search was performed in 03/2022 using PubMed to search for clinical trials that mentioned in the title and/or abstract selected cancer (CLL, MM, or NHL) treatments covering 12 classes of drugs, including B-lineage monoclonal antibodies, CAR T therapies, proteasome inhibitors, kinase inhibitors, immunomodulators, antimetabolites, anti-tumor antibiotics, alkylating agents, Bcl-2 antagonists, histone deacetylase inhibitors, vinca alkaloids, and selective inhibitors of nuclear export. To be included, a publication had to report at least one of the following: percentages of patients with any grade and/or grade ≥3 infections, any grade and/or grade ≥3 neutropenia, or hypogammaglobulinemia. From the relevant publications, the percentages of patients with lymphocytopenia and specific types of infection (fungal, viral, bacterial, respiratory [upper or lower respiratory tract], bronchitis, pneumonia, urinary tract infection, skin, gastrointestinal, and sepsis) were collected., Results: Of 89 relevant studies, 17, 38, and 34 included patients with CLL, MM, and NHL, respectively. In CLL, MM, and NHL, any grade infections were seen in 51.3%, 35.9% and 31.1% of patients, and any grade neutropenia in 36.3%, 36.4%, and 35.4% of patients, respectively. The highest proportion of patients with grade ≥3 infections across classes of drugs were: 41.0% in patients with MM treated with a B-lineage monoclonal antibody combination; and 29.9% and 38.0% of patients with CLL and NHL treated with a kinase inhibitor combination, respectively. In the limited studies, the mean percentage of patients with lymphocytopenia was 1.9%, 11.9%, and 38.6% in CLL, MM, and NHL, respectively. Two studies reported the proportion of patients with hypogammaglobulinemia: 0-15.3% in CLL and 5.9% in NHL (no studies reported hypogammaglobulinemia in MM)., Conclusion: This review highlights cancer treatments contributing to infections and neutropenia, potentially related to SID, and shows underreporting of hypogammaglobulinemia and lymphocytopenia before and during HM therapies., Competing Interests: Literature searches, article screening, data abstraction, and medical writing support was provided by Meridian HealthComms Ltd (Manchester, UK) in accordance with Good Publication Practice guidelines and funded by CSL Behring. SJ has received support for conferences, speaker, advisory boards, trials, data and safety monitoring boards, and projects with CSL Behring, Takeda, Swedish Orphan Biovitrum, Biotest, Binding Site, Grifols, BPL, Octapharma, LFB, Pharming, GSK, Weatherden, Zarodex, Sanofi, and UCB Pharma. SG has received research funding from Miltenyi Biotec, Takeda, Celgene, Amgen, Sanofi, Johnson and Johnson, and Actinium and is on the advisory boards for: Kite Pharmaceuticals, Celgene, Sanofi, Novartis, Johnson and Johnson, Amgen, Takeda, Jazz Pharmaceuticals, Actinium Pharmaceuticals, and CSL Behring. TK has received support, never on a personal account, for conferences, speaker bureaus, advisory boards, trials, data and safety monitoring boards, and projects with Sanofi, Takeda, BMS, Johnson & Johnson, MSD, Novartis, Gilead, Octapharma, and CSL Behring. HML has received consultancy fees and support for advisory boards from CSL Behring and Actinium Pharmaceuticals; is a consultant, promotional speaker, and a member of the advisory boards for Jazz Pharmaceuticals and Seattle Genetics; is a member of the data safety and monitoring boards for BMS, BioSight, and Celgene; is a promotional speaker for AstraZeneca; has received consultancy fees and has stock options with Partner Therapeutics; and has received consultancy fees from Pluristem. SSM has received support for an advisory board and speaker bureaus with CSL Behring. RR has received support for advisory boards, data and safety monitoring boards, and speaker bureaus with Janssen Cilag, BMS, Celgene, Takeda, CSL Behring, and Octapharma. DCV has received salary support from Fonds de Recherche du Québec - Santé Senior Clinician-Scientist scholar program; has received clinical trial support from CSL Behring, Cidara Therapeutics, and Moderna; has received honoraria for advisory board consultations or speaker presentations from Astra Zeneca, CSL Behring, Merck Canada, Moderna, Novartis Canada, Qu biologics, and UCB Biosciences GmbH; and has a patent application pending Electronic Filing System ID: 40101099 and a report of invention submitted to McGill University Track code: D2021-0043., (Copyright © 2023 Jolles, Giralt, Kerre, Lazarus, Mustafa, Ria and Vinh.)