Cancer type influences likelihood of breakthrough COVID-19 infection

The risk of SARS-CoV-2 breakthrough infection in vaccinated cancer patients differs by cancer type, according to a recently published study. “Even when cancer patients are vaccinated, it doesn’t mean they’re totally protected. They have a higher breakthrough infection rate than noncancer patients,” said Dr. Nathan Berger, professor of medicine at Case Western Reserve University School of Medicine. Berger was coauthor of a study investigating the risk of breakthrough SARS-CoV-2 infection, rates of hospitalizations and associated mortality in vaccinated cancer patients. Findings were published in JAMA Oncology. The study showed that cancer patients who experienced breakthrough infections had an increased risk of hospitalization or dying. Patients with cancer had significantly increased risk for breakthrough infections when compared to patients without cancer. Read: Lung cancer detected earlier in breast cancer patients “It’s important to encourage cancer patients to continue mitigation such as social distancing, avoiding crowds and masking, even if they’re following vaccination recommendations,” he said. Still, the findings could be taken into account when developing protective strategies for vaccinated patients with specific cancers, especially those undergoing active cancer care, Berger said. The study was designed to characterize breakthrough infections, hospitalizations, and mortality in vaccinated patients for all cancers, with a focus on the 12 most common cancers in the US: bladder, breast, colorectal, endometrial, hematologic, kidney, liver, lung, pancreatic, prostate, skin, and thyroid cancer. Using the TriNetX Analytics network platform, a database containing data of 90 million patients from 66 health care organizations across the US, researchers extracted details for 45,253 vaccinated patients with cancer. Subjects had a mean age of 68.7 years, 53.5% were female, 3.8% were Asian individuals, 15.4% were Black, 4.9% were Hispanic, and 74.1% were White. Data were compared to those for 590,212 vaccinated patients without cancer. Vaccinated subjects had at least two COVID-19 vaccinations between December 2020 and November 2021 and had not contracted SARS-CoV-2 infection previously. The overall cumulative risk of breakthrough infections in patients with all cancers was 13.6%. It was found that breakthrough infections occurred most commonly in those with pancreatic (24.7%), liver (22.8%), lung (20.4%), and colorectal (17.5%) cancers. Those with the lowest risk for breakthrough infections were thyroid (10.3%), endometrial (11.9%), and breast (11.9%) cancers, compared to only 4.9% in the non-cancer population. The overall risks did not differ based on race or ethnicity for 12 specific cancer types. Patients with cancer were 1.24 times more likely to experience breakthrough infections than non-cancer patients. In addition, patients who had medical encounters for cancer within the past year had higher risk for breakthrough infections than those who did not. Read: Major study shows the need to improve how scientists approach early-stage cancer research “The rate is higher in patients who are in their first year post-diagnosis which is when they’re usually getting their most intensive therapy,” Dr. Berger said. “If there is a breakthrough infection, they’re more susceptible to the more serious effects in terms of hospitalization and death.” However, he said the study did not look specifically at the question of which cancer treatments may affect breakthrough infections, but he noted that other studies have reported that some types of treatments may be associated with lower effectiveness of the vaccines due to effects on the immune system. Among all cancer types, the overall hospitalization rate was 31.6% in patients with breakthrough infections, but only 3.9% for patients without breakthrough infections. The overall mortality rate was 6.7% in cancer patients with breakthrough infections, and 1.3% in matched patients with cancer with no breakthrough infections. Among patients without cancer, the overall hospitalization risk was 25.9% in patients with breakthrough infections, higher than the risk of 3.0% in matched patients without breakthrough infection, the study said. The overall mortality risk was 2.7% in patients without cancer who had breakthrough infections, higher than 0.5% in matched patients without cancer who had no breakthrough infections. Read: ctDNA test in question for detecting colorectal cancer recurrence “Interestingly, findings from this study showed that the overall risk for breakthrough infection among patients with hematologic cancers was lower than that for patients with colorectal, lung, bladder, kidney, liver, and pancreatic cancer. These results suggest that the levels of impaired antibody response to COVID-19 vaccines in patients with cancer may not directly correlate with breakthrough infections,” the study said. On another note, the study also found that vaccination eliminated race-based differences in terms of outcomes. Other studies have shown that, overall, racialized populations tend to have worse outcomes in unvaccinated people with COVID-19 infection. “Vaccination eliminated disparity… That means whatever problems there may be with exposure in different ethnic groups, the vaccine takes care of that. When we started, we expected to see that the ethnic disparity would persist and we were pleasantly surprised to see that it was eliminated,” Dr. Berger said in an interview. Read: Few newly approved cancer drugs change first-line treatments The study stated that “no significant racial and ethnic difference in risks for breakthrough infections was observed in vaccinated patients with cancer for all 12 cancer types, suggesting that vaccination may have narrowed or eliminated the racial and ethnic disparities in SARS-CoV-2 infections in patients with cancer for the population in this study.” Another recent study by a different US research group in the Journal of Clinical Oncology using data from National COVID Cohort Collaborative (N3C) to identify breakthrough infections between December 1, 2020, and May 31, 2021 found that patients with hematologic malignancies were actually at higher risk for developing breakthrough infections and severe outcomes when compared to those with other cancers. Here, it was found vaccinated cancer patients had a significantly decreased risk for breakthrough infections. The researchers studied 6,860 breakthrough cases which were identified within the N3C-vaccinated population—of these 1,460 (21.3%) were people with cancer. The researchers reported that breakthrough risk was reduced after the second vaccine dose for all cancers, especially in patients with multiple myeloma, with the Moderna vaccine showing more benefit than the Pfizer vaccine. It added that “Medications with major immunosuppressive effects and bone marrow transplantation were strongly associated with breakthrough risk among the vaccinated population.” Read: Study examines opportunistic salpingectomy as tool to reduce ovarian cancer risk

Cancer type influences likelihood of breakthrough COVID-19 infection

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