Over half (56%) of employers were worried about cancer and serious ill-health affecting their workforce, research from GRiD found.
Staff shared these concerns, with a quarter (25%) of workers over 60 and 15% of all ages saying they were worried about serious ill-health such as cancer.
Some told their employer about a diagnosis due to treatment, absence or adjustments, but others chose to keep it private.
Katharine Moxham, spokesperson for GRiD, said: “Cancer remains one of the most significant health challenges facing today’s workforce, yet for many employers its true impact is still only partially visible.
“This research highlights the scale of concern and the opportunity for employers to do more to ensure every individual feels supported and able to access the help they need.
“Cancer touches each person in their own way. Some need support at the very start, some partway through, some after treatment ends, and some from the first moment to the last.”
Moxham added: “Support should never be something people stumble across by chance or discover halfway along.
“It should be visible, clear, and present from the beginning, ready for anyone who chooses to lean on it.”