What is the effect of the COVID-19 pandemic on cancer and cancer treatment? Is the COVID-19 vaccine safe for patients diagnosed with cancer in active treatment?
Since the early days of the pandemic, there have been many questions about how cancer patients would fare if they became infected with SARS-CoV-2, the virus that causes COVID-19. Some of the concerns were due, to the effects that cancer and its treatments can have on the immune system. Other questions involved the immediate access to care following disruptions associated with the COVID-19 pandemic. And what will be the effect of the gaps in cancer screenings documented throughout the country 
The COVID-19 pandemic has caused a major setback in screening. One study, using data from a large medical claims clearinghouse database representing 5%-7% of the Medicare fee-for-service population to characterize changes in the utilization of cancer care services, helped gain insight into the impact of COVID-19 on the US cancer population. The data included identification of new patients, gaps in access to care, and disruption of treatment journeys.
The data showed that, in comparison with the baseline period one year earlier, there was a substantial decrease in cancer screenings, visits, therapy, and surgeries, with variation by cancer type and site of service. According to the authors of the study, at the peak of the pandemic screenings for breast, colon, prostate, and lung cancers were lower by 85%, 75%, 74%, and 56%, respectively.
The expected impact of this decrease is that if this delay in diagnostics and treatment is not addressed, it will result in a major increase in cancer morbidity and mortality for years to come.
Effect of COVID-19 vaccines
With the availability of COVID-19 vaccines, concerns have shifted to concerns about the safety and effectiveness of vaccination of patients diagnosed with cancer. One study, in which two hundred and sixty-four participants agreed to attend an educational webinar about COVID-19 vaccines, looking at the causes for vaccine hesitancy, found that a fear of side effects was the chief reason for such hesitancy.
This fear, in part based on the fact that both anticancer therapies and the underlying malignancy itself may lead to significant immunosuppression, can pose a particular challenge for vaccination strategies in these patients. However, researchers in both Europe and the United States have confirmed that vaccination among cancer patients, works very well and is safe.
Prioritizing vaccination in cancer patients
Researchers at the Klinik für Innere Medizin II, Abteilung für Hämatologie und Internistische Onkologie, Universitätsklinikum Jena, in Jena, Germany, the Hämato-Onkologie Germering, Schwerpunktpraxis des Tumorzentrums München, Germering, Germany, the Universitätsklinikum Heidelberg, Heidelberg, Germany and the Charité – Universitätsmedizin Berlin, Berlin, Germany, looked COVID-19 vaccines available in Germany. The results of their study were published in Der Onkologe : Organ der Deutschen Krebsgesellschaft (Beilage für Onkologen).
The mechanism of action of these vaccines, they observed, relies on the induction of the production of virus-specific proteins by human cells and the following activation of a specific adaptive immune response. And because these vaccines demonstrated excellent protection against severe COVID-19, these vaccination have been prioritized for cancer patients and medical personnel in Germany.
Because of their mechanism of action, vaccination prior to initiation of anticancer therapy is considered ideal in patients who are newly diagnosed. In addition, due to the significant risk of severe COVID-19 in cancer patients, vaccination is also strongly recommended for patients already undergoing anticancer therapy in whom the immune response might be reduced.
The researchers looked at two particular patient cohorts, one group of stem cell transplant recipients and another group of patients treated with B‑cell depleting agents. The preliminary data of a German study demonstrated that based on the rates of seroconversion following a single shot of vaccine in cancer patients, repeat vaccination regimens might be preferable in cancer patients. 
Another study, published June 5, 2021, in the journal Cancer Cell also aims to allay fears against vaccination.
In this study, funded by the National Cancer Institute (NCI) and the NCI Community Oncology Research Program (NCORP), researchers reviewed 200 patients with a wide spectrum of cancer diagnoses, researchers at Montefiore Health System and Albert Einstein College of Medicine in the Bronx, NY, found that after full vaccination, 94% of patients overall demonstrated seroconversion, which was determined by the presence of antibodies to the SARS-CoV-2 spike protein. Response rates were very high among patients with solid tumors and were lower in people with certain blood cancers, but even the majority of those patients mounted an immune response.
“Studies from early in the pandemic found that cancer patients who get COVID-19 have higher rates of morbidity and mortality compared to the general population,” said senior co-author Amit Verma, director of the Division of Hemato-Oncology at Montefiore and professor of medicine and of developmental and molecular biology at Einstein, and associate director, translational science, Albert Einstein Cancer Center.
“We really need efforts to protect these vulnerable patients from infection. This study should help people feel reassured that these vaccines work very well, even in those receiving chemotherapy or immunotherapy,” Verma explained.
“This study confirms that there is no need for patients to wait for vaccination until they finish their chemotherapy or immunotherapy,” says senior co-author Balazs Halmos, director of the Multidisciplinary Thoracic Oncology Program at Montefiore, professor of medicine at Albert Einstein College of Medicine, and a member of the Albert Einstein Cancer Center (AECC).
“The side effects from vaccination seen in these populations were not substantially worse than in other groups. Not a single patient had to go to the emergency room or be admitted to the hospital because of side effects from the vaccines,” Halmos added.
This study was the largest of its kind to look at seroconversion rates in cancer patients who have been fully vaccinated. Previous studies have looked at much smaller populations or have analyzed antibody levels after only the first dose of two-dose vaccines.
In serum tests to look for IgG levels after vaccination, the researchers found that among patients with solid tumors, 98% showed seroconversion. Among patients with hematologic cancers, the rate of seroconversion was 85%.
Patients receiving some treatments fared worse than others. Those receiving therapies for blood cancers that work by killing B cells (such as rituximab or CAR T therapies) had seroconversion rates of 70%. For those who had recently had bone marrow or stem cell transplants, the rate was 74%. But those rates were still much higher than expected, the researchers say.
“Although those receiving treatments that affect B cells didn’t do as well, patients with blood cancers that affect the myeloid cells rather than the lymphoid cells had a pretty good response with regard to seropositivity,” says first author Astha Thakkar, a Montefiore hematologic oncology fellow.
“This includes people with acute myeloid leukemia and myelodysplastic syndrome,” Thakkar further noted.
The researchers say that one reason their data are so significant is that they include patients who had a broad range of cancers and who were undergoing a number of different treatments.
“The patients themselves were also diverse and were representative of the patients we treat in the Bronx,” Halmos explained. “About one-third were Black and 40% were Hispanic.”
“Vaccination among these populations has been lower, even though these groups were hardest hit by the pandemic,” Verma said.
“It’s important to stress how well these patient populations did with the vaccines,” she concluded.
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