Oxford and Birmingham Universities teamed up to study hundreds of UK cancer patients who were diagnosed with the virus.
They found the mortality rate in cancer patients who are assessed or treated in hospital with COVID-19 is not significantly affected by chemotherapy or other anti-cancer treatments.
The data 'strongly shows' that cancer COVID-19 mortality is principally driven by advancing age and the presence of other non-cancer co-morbidities.
Published in The Lancet, the study was devised by a steering committee of the UK Coronavirus Cancer Monitoring Project (UKCCMP) which launched in March, and collects information on UK cancer patients who are diagnosed with COVID-19.
The project was set up to evaluate whether recent (within 4 weeks) or current chemotherapy or other active cancer treatment (radiotherapy, immunotherapy or hormonal therapy) impacted upon mortality.
55 cancer centres across the UK reported into the UKCCMP, analysing the outcomes of the first 800 COVID19-positive cancer patients.
Results found 169 of the 800 were reported as having no comorbidities (underlying health conditions) other than cancer.
In the remaining 631 patients, other comorbidities included hypertension, diabetes, cardiovascular disease and chronic obstructive pulmonary disease.
In terms of COVID-19 disease trajectory, over half of patients followed a mild disease course.
As in the general population, patients who were older and suffered other co-morbidities were at increased risk of death compared to younger patients without any other underlying comorbidities.
The overall mortality rate was 28%. Recent receipt (within 4 weeks) of chemotherapy was not associated with an increased risk of death.
Dr Lennard Lee, Medical Oncology Clinical Academic from the University of Birmingham, said: "This project is a great illustration of what can be achieved by the UK oncology community. We have joined forces to learn from each other and answer the most pressing questions for cancer patients.
"The UKCCMP projects will be crucial in providing the necessarily tools to enable to identify and mitigate risks to cancer patients now and in any possible pandemic phases. This will ensure the highest levels of cancer care will continue to be provided across the UK."
Professor Rachel Kerr from the University of Oxford said: "I am incredibly proud of how hard my colleagues have worked to deliver this hugely important and timely study.
"The team comprises a wealth of expertise from consultant oncologists to computational data scientists, but actually also could not have been delivered without the dedication of our junior doctors and medical and biological science undergraduates.
"Sterling team work which has produced a really critical answer for our understandably concerned cancer patients and community."
The researchers hope the study will be reassuring for cancer patients.