COVID-19 among cancer patients. What we know so far?

In December 2019, a novel coronavirus disease (COVID-19) emerged in Wuhan, a city in the Hubei, Province of China. It rapidly spread in an epidemic fashion throughout China, followed by rapid increasing number of cases in many countries throughout the world, including Brazil.(1) WHO has declared COVID-19, caused by SARS-CoV-2, a public health emergency of international concern.(1)

It is well known that cancer patients are more susceptible to infection than the general population due to their systemic immunosuppressive state caused by either the malignancy or anticancer treatments.(2) Therefore, it is expected that oncologic patients have an increased risk of COVID-19 infection with possible worse clinical outcomes. We aim at reviewing current evidence of COVID-19 disease among cancer patients.

The Chinese Center for Disease Control and Prevention published the largest case series of COVID-19 in China (n=72314).(3 4) Most cases (81%) were classified as mild, while 14% were severe (dyspnea, respiratory frequency =30/min, blood oxygen saturation =93%, partial pressure of arterial oxygen to fraction of inspired oxygen ratio <300, and/or lung infiltrates >50% within 24-48 hours), and 5% critical (respiratory failure, septic shock, and/or multiple organ dysfunction or failure).(4) The overall case-fatality rate was 2.3%, which increased to 14.8% among patients aged =80 years and 8.0% among those aged 70-79 years. In addition, case-fatality rate was elevated among those with preexisting comorbid conditions, including 5.6% for cancer.(4)

Another study including 1099 patients with laboratory-confirmed COVID-19 from 552 hospitals in China evaluated admission rate to intensive care unit (ICU), use of mechanical ventilation (MV), or death as the primary endpoint.(5) Patients with cancer comprised only 0.9% of all patients (n=10), with 30% considered as severe. Only one patient satisfied the primary composite endpoint.(5)

In parallel, Chinese efforts established a prospective cohort to monitor national COVID-19 cases and analyzed 2007 laboratory-confirmed and admitted cases.(6) After excluding 417 cases with insufficient records, 18 of 1590 COVID-19 cases had a history of cancer. Among those 18 patients, 5 had lung cancer (2 on targeted therapy, 2 on chemotherapy and 1 in routine follow-up), 4 colorectal (all on routine followup), 3 breast (all on routine follow-up), 2 bladder (all on routine follow-up), 1 lymphoma (no information available), 1 adrenal (3 weeks after operation), 1 thyroid (on TSH inhibition therapy), and 1 renal cancer (on immunotherapy). Therefore, 75% of the infected patients were cancer survivors in routine follow-up, who may not be truly immunosuppressed when compared to those on active treatment.(6)

Compared with non-cancer patients, oncologic patients were older (mean 63.1 vs 48.7, p <0.001), more likely to have a history of smoking (22.2 vs 6.8%, p =0.032), developed more polypnea (47.1 vs 23.5%, p =0.039), and had more severe baseline computed tomography abnormalities (94.4 vs 70.8%, p =0.033). Among those cancer patients, 39% had a severe event (defined as ICU admission, VM, or death) compared to 8% of non-cancer patients ( p =0.0003). Other characteristics, such as gender, presence of other comorbidity and abnormalities in X-rays were similar between cancer and non-cancer patients.(6)

As expected, patients who underwent active systemic treatment (chemotherapy or immunotherapy) or surgery in the past 30 days had a non-statistically significant higher risk of severe events than others (75 vs 43%). After logistic regression adjusting for important factors, treatment in the past month was statistically related to severe outcomes (OR 5.34, 95% CI 1.80-16.18, p =0.0026). In this nationwide Chinese study, cancer history was actually the highest risk for developing severe events, which was further increased in older patients (OR 1.43, 95% CI 0.97-2.12, p =0.072). The authors also reported that cancer patients had a median time to severe events of 13 days as compared to 43 days for those without cancer ( p <0.0001), indicating a more rapid deterioration.(6)

Unfortunately, data on COVID-19 among cancer patients is still scarce with less than 30 described cases. Along with the small sample size of only Chinese patients, there is a large amount of heterogeneity with several cancer types and different oncologic treatments. In addition, cancer cases were not fully described, many of them were already cured with no clear immunosuppression, and many had history of smoking and were older than non-cancer patients, which might explain the worse outcomes.

In conclusion, although cancer patients with COVID-19 are expected to have a poorer outcome, data remains scarce. We are still learning from this outbreak and international collaboration is necessary for better describe the characteristics and outcomes of COVID-19 disease among cancer patients.