A substantial proportion of patients who are diagnosed with cancer have a history of a previous malignancy.
According to new findings, about a quarter of patients with cancer aged 65 years and older and 11% of younger adults had had a previous malignancy. The prevalence ranged from 4% to 37% in a cohort of more than 740,000 patients, varying according to age and cancer type.
Most of the prior cancers had been diagnosed in a different cancer site.
“As the cancer survivor population continues to grow, understanding the nature and impact of a prior cancer is critical to improving trial accrual, generalizability of results from trials and observational studies, disease outcomes, and patient experience,” say the authors, led by Caitlin C. Murphy, PhD, MPH, from the University of Texas Southwestern Medical Center, Dallas.
The study was published online November 22 in JAMA Oncology.
The population of cancer survivors is rapidly growing and expected to reach 26.1 million by 2040. However, the authors point out, cancer survivors are all too often excluded from cancer clinical trials.
As an example, more than 80% of lung cancer trials affiliated with the National Cancer Institute will exclude a patient with a history of a previous malignancy. As many as 25% of patients with newly diagnosed lung cancer may end up being excluded from participating trials because of these exclusion criteria.
“Excluding cancer survivors from clinical trials is not evidence-based,” said Dr Murphy. “Some trials exclude all cancer survivors, and others exclude patients based on the type, stage, or timing of the prior cancer.”
“We believe this common practice may arise from the assumption that patients with a prior cancer have higher mortality, which could hinder study conduct and bias trial outcomes,” Dr Murphy told Medscape Medscape News. “Our team’s earlier work in lung cancer suggests that a prior cancer diagnosis is typically associated with either a survival advantage, or no difference in survival, compared to patients without a prior cancer.”
She pointed out that based on their research, ECOG-ACRIN (Eastern Cooperative Oncology Group–American College of Radiology Imaging Network), a member of the National Clinical Trials Network, removed prior cancer from the standard list of exclusion criteria for metastatic lung cancer trials.
“We need more evidence about patients with other types of cancer before reconsidering whether and how best to include patients with prior cancer in trials,” Dr Murphy said.
Second Cancers Common
Previous research has already shown that cancer survivors face a risk for not only a recurrence of their primary cancer but occurrence a second malignancy. A study published last year found that in the United States, more than 8% of adults diagnosed with the most common cancers will subsequently develop a second malignancy of any type, including rare cancers.
More disturbingly, second cancers were often fatal: In that study, more than half of patients (55%) died of their second cancer, while 13% died of their first cancer.
The risk for a second cancer can be higher in certain groups of survivors. For example, patients with Hodgkin’s lymphoma, who also have an increased cardiovascular risk, were reported to have a cumulative incidence of a second cancer of 48.5% after 40 years of survival.
In the current paper, Dr Murphy and colleagues examined the prevalence of prior cancer among individuals with newly diagnosed cancer.
They used the Surveillance, Epidemiology, and End Results program of cancer registries (1975 to 2013) and identified 740,990 persons who received a cancer diagnosis from January 2009 through December 2013. They estimated the prevalence of prior cancer by age and incident cancer type.
Of the 765,843 incident cancer cases included in the analysis, 141,021 (18.4%) represented a second-order or higher primary cancer.
Prevalence of prior cancer was higher in those aged 65 years and older than in younger adults (25.2% vs 11%), and cancer type varied by age group. Among younger patients, the most prevalent prior cancers included myeloid and monocytic leukemia (24.8%); cancer of the anus, anal canal, and rectum (18.2%); cancer of the cervix and other female genital organs (eg, vagina, vulva; 15.0%); and lung and other respiratory (14.6%) cancers.
For older patients, the most prevalent cancers were melanoma (36.9%), myeloid and monocytic leukemia (36.9%), bone and joints (34.0%), and urinary bladder and other urinary organs (32.5%).
In both cohorts, most prior cancers generally occurred in a different site.
“Right Size” Clinical Trial Approach
So how can these data help improve care for the cancer survivor? In an invited commentary, Nancy E. Davidson, MD, from the Fred Hutchinson Cancer Research Center in Seattle, Washington, outlines the importance of these findings.
First and foremost, she notes, “they reinforce our common knowledge that diagnosis of a first cancer is frequently associated with diagnosis of a second cancer because of shared underlying risk factors like tobacco use, obesity, or human papillomavirus…exposure.”
Additionally, the treatment regimen for the previous cancer can lead to the development of a subsequent second cancer.
Second, writes Dr Davidson, this analysis is a reminder of the importance of taking both “a nuanced and holistic approach to health care and clinical investigation.”
Third, these data should prompt clinicians and investigators to revisit the long-standing and currently accepted policies of excluding many otherwise suitable patients with a history of previous early-stage invasive cancer from participating in clinical trials.
“In particular these restrictions may greatly limit participation of older patients, the very population where cancer is most commonly diagnosed and where we are most in need of strong evidence to guide treatment,” Dr Davidson says.
This plea to “right size” the approach to clinical trial eligibility is not brand new, she adds, but “it is ever more important in a climate of biologically based therapies that will be relevant for only a fraction of the patient population.”
The study is supported by the National Cancer Institute and the National Center for Advancing Translational Sciences at the National Institutes of Health. The study authors and Dr Davidson have disclosed no relevant financial relationships.
JAMA Oncol. Published online November 22, 2017. Abstract
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