Screening for Early Therapy-Related Cancer Susceptibility

Abstract

Therapy-related cancers are a significant consequence of modern oncologic and non-oncologic therapies, particularly as survivorship increases. Early identification of individuals at increased risk is essential for optimizing long-term outcomes. This review explores the epidemiology, pathophysiology, risk factors, clinical features, diagnosis, treatment and management, as well as recent advances and guideline recommendations regarding the screening for early therapy-related cancer susceptibility. The goal is to provide a comprehensive, evidence-based overview that will inform clinical practice among healthcare professionals.

Introduction

Therapy-related cancers, including therapy-related myeloid neoplasms (t-MNs) and secondary solid tumors, represent a growing clinical challenge. With advances in curative therapies for primary malignancies and benign conditions, patient longevity has increased, but so too has the incidence of secondary malignancies attributed to earlier treatments. Early detection of susceptibility to therapy-related cancers could enable tailored interventions, surveillance, and prophylaxis, reducing morbidity and mortality in high-risk populations. This article reviews the latest evidence on screening strategies, risk stratification, and practical recommendations for clinicians managing patients with potential therapy-related cancer susceptibility.

Epidemiology / Disease Burden

The incidence of therapy-related cancers has risen in parallel with improved survival rates for primary diseases. Therapy-related myeloid neoplasms, including therapy-related acute myeloid leukemia (t-AML) and myelodysplastic syndrome (t-MDS), account for up to 10-20% of all AML cases in adults, with a median latency of 5-7 years post-exposure. Secondary solid tumors, such as breast, thyroid, or lung cancer, are also prevalent, particularly among survivors of childhood cancers. Population-based studies suggest that survivors of Hodgkin lymphoma, pediatric acute lymphoblastic leukemia, and certain autoimmune diseases treated with cytotoxic or immunosuppressive agents have a substantially elevated lifetime risk of secondary malignancies. The burden is magnified by the often poorer outcomes and limited therapeutic options associated with therapy-related cancers compared to de novo counterparts.

Pathophysiology

The development of therapy-related cancers is multifactorial, involving direct DNA damage, mutagenesis, and disruption of cellular repair mechanisms. Alkylating agents, topoisomerase II inhibitors, ionizing radiation, and stem cell transplantation are principal contributors. These exposures induce chromosomal aberrations, such as deletions and translocations, and foster clonal hematopoiesis of indeterminate potential (CHIP), which may evolve into overt neoplasia. Recent genomic studies have identified common pathogenic mutations in genes such as TP53, RUNX1, and ASXL1 in t-MNs. Moreover, germline predisposition, such as BRCA1/2 or TP53 mutations (Li-Fraumeni syndrome), can synergistically increase susceptibility when exposed to genotoxic therapies. Epigenetic modifications and impaired immune surveillance further augment risk.

Risk Factors

Risk factors for therapy-related cancer susceptibility are multifactorial and include both treatment-related and host-specific variables. Cumulative dose and intensity of cytotoxic chemotherapy (especially alkylators and epipodophyllotoxins), radiation dose and field, age at exposure (younger patients are at higher risk), and prior stem cell transplantation are established contributors. Genetic susceptibility, pre-existing CHIP, inherited cancer syndromes, and environmental exposures (such as tobacco use) modulate risk further. Notably, recent insights reveal that even low-dose exposures can be hazardous in genetically predisposed individuals, underscoring the need for individualized risk assessment.

Clinical Features

Therapy-related cancers may present insidiously, often years after the inciting therapy. t-MNs typically manifest with cytopenias, fatigue, infections, or bleeding, while secondary solid tumors may present as new masses or organ dysfunction. Clinical vigilance is especially warranted in patients with atypical or persistent symptoms following prior cytotoxic therapy. Importantly, therapy-related malignancies often have unique cytogenetic and molecular features, such as complex karyotypes or specific translocations (e.g., 11q23 in t-AML), which may inform diagnosis and prognosis. Surveillance strategies should consider latency periods and symptomatology associated with specific secondary cancer types.

Diagnosis

Diagnosis of therapy-related cancers relies on a combination of clinical history, laboratory testing, and advanced molecular diagnostics. Comprehensive review of prior treatment exposures is critical. Hematologic malignancies are confirmed via peripheral blood counts, bone marrow evaluation, flow cytometry, cytogenetics, and next-generation sequencing to define mutations and clonal evolution. For solid tumors, imaging (CT, MRI, ultrasound) and tissue biopsy remain standard. Novel biomarkers, such as circulating tumor DNA and CHIP-associated mutations, are under investigation for early detection. Risk-adapted screening protocols tailored to therapy type, cumulative dose, and genetic susceptibility are increasingly advocated, particularly in high-risk survivors.

Treatment & Management

Management of therapy-related cancers is complex, often limited by prior toxicities and comorbidities. t-MNs are generally associated with poorer prognosis than de novo cases and may require intensive chemotherapy, hypomethylating agents, or allogeneic hematopoietic cell transplantation. The latter remains the only potentially curative option for many patients, though eligibility is often constrained by age and organ function. Secondary solid tumors are managed according to site-specific protocols, with consideration of prior radiation fields and cumulative organ doses. Multidisciplinary care, including genetic counseling and supportive care, is essential for optimizing outcomes. Preventive strategies, such as minimizing unnecessary cytotoxic exposure and promoting healthy lifestyle modifications, are critical components of survivorship care.

Recent Advances / Emerging Therapies

Recent years have seen significant advances in the early identification and management of therapy-related cancer susceptibility. High-throughput sequencing enables detection of CHIP and germline mutations prior to therapy initiation, facilitating risk stratification. Polygenic risk scores and machine learning algorithms are being explored to refine prediction models. Prophylactic interventions, such as alternative non-genotoxic therapies, dose reduction, or the use of targeted agents (e.g., PARP inhibitors for BRCA-mutated patients), offer promise in high-risk cohorts. Liquid biopsy approaches for minimal residual disease (MRD) and early relapse detection are also under development. Collaborative registries and prospective trials are clarifying the natural history and optimal management strategies for therapy-related cancers.

Guideline Recommendations

Leading organizations, including the American Society of Clinical Oncology (ASCO), National Comprehensive Cancer Network (NCCN), and Children's Oncology Group (COG), emphasize individualized risk assessment and tailored surveillance for therapy-related cancer susceptibility. Guidelines recommend baseline and periodic screening for hematologic parameters, targeted imaging, and consideration of genetic counseling for survivors with significant exposure history or family predisposition. Pre-therapy screening for CHIP and germline mutations is increasingly advocated in high-risk settings. Shared decision-making and multidisciplinary involvement are integral to guideline-concordant care. Ongoing updates to recommendations reflect the rapidly evolving evidence base and emerging screening technologies.

Conclusion

The increasing burden of therapy-related cancers necessitates vigilant identification of individuals at heightened risk. Advances in molecular diagnostics, risk modeling, and targeted interventions are transforming the landscape of early screening and prevention. Clinicians must integrate evolving evidence and guideline recommendations into survivorship care to mitigate the impact of therapy-related malignancies. Future research should focus on refining risk stratification tools, validating novel biomarkers, and optimizing surveillance protocols to improve outcomes for this vulnerable patient population.