The stigma around cancer has started to diminish, thanks to greater awareness and education, as well as improved survival rates. And the Equality Act protects employees with cancer from discrimination, so, legally, they are not required to inform their employer they have disease.
But this means if an employee does not tell his or her manager about the illness and it affects their ability to work, it can lead to disciplinary action - and the law does not require the employer to make any adjustment for the employee if it is unaware of the situation.
So while the employer must make 'reasonable adjustments' to support employees who do report their illness, how can it best uphold its duty of care? And if the employer does discover an employee has cancer, where does it seek help or advice?
Line managers need staff permission to contact medical professionals and, with long-term absence a strong possibility, there are cost factors involved too.
"Losses to the economy due to cancer survivors who are unable to return to work amount to £5.3 billion, but losses to individual employers are difficult to measure," explains Mark Ratnarajah, business development manager at Capita Wellbeing and Health.
"The direct recruitment cost of a new position is £4,300 per employee and it takes time to recruit - six to 11 weeks. There are also indirect costs, unique to an organisation, such as loss of productivity, intellectual property and knowledge. It is a significant expense," adds Ratnarajah.
Employee engagement, he believes, is at the core of the matter, given approximately four out of 10 people are diagnosed with cancer in their working lives - and at least 50% have to change their jobs or leave work because of this.
Ratnarajah explains: "It is very much about the culture of the organisation and about the confidence employees have in talking freely about these matters.
"Some people may be embarrassed by some of the consequences of treatment, such as hair loss or weight gain. These can result in discrimination. So it is important employers provide some sort of facility - such as an employee assistance programme - or some form of counselling or support network."
Just over a third (36%) of employees in the private sector have occupational health benefits. Such access to vocational rehabilitation, physiotherapy, workplace assessment or symptom relief means people feel more supported to deal with the reality, physical and mental, of cancer.
However, there are a lot of line managers who don't know what they are supposed to do from a legal, health or psychological perspective - and research this year from Macmillan Cancer Support shows 56% of line managers believe there is a lack of awareness of the advice available to deal with these things.
Added to these problems is the question of NHS support, both during and after treatment.
A 2011 YouGov survey for Macmillan reveals two-thirds of cancer patients in Scotland left hospital after initial treatment, with no information about how to cope with the effects of cancer and its treatment.
A further 65% did not get any ongoing support from a cancer nurse specialist. And 57% said they were not given information about who to contact if they had any concerns about their illness.
"Our view with cancer care is that there is a postcode lottery. But there are pockets of excellence in the NHS and the employer should be looking at what the NHS does locally," advises Charlie MacEwan, director at private medical insurance (PMI) provider, WPA.
MacEwan believes the question of support and advice post-treatment is very much a team effort.
"The whole medical profession should be supporting the patient to get the information they need. And the employer is part of that team, as is the individual - they are the one in the driving seat," he adds.
Where the NHS falls down too is in the availability and cost of certain cancer drugs. The Government's announcement last year of a £200 million cancer drugs fund has been touted as contributing towards the cost of expensive 'breakthrough' medication. But the scheme is mired in controversy, with regional variations creating huge inequalities.
Naomi Saragoussi, senior consultant at HR consultancy Mercer, says employers offering PMI, including cancer cover, to staff are faced with a potentially expensive situation because of the high cost of these drugs.
"It can go on over years," she says. "But cancer is very emotive. It is quite rare to find it totally excluded from PMI. And generally most people with cancer are able to work at certain times between treatments. You are not talking about long-term disability.
"Until the Government's Cancer Drug Fund is finalised, employers should keep a watchful eye on the private medical market. Going forward, they should look at using the NHS and the private medical sector together, one supporting the other."
There are, of course, different types of products employers might offer staff, such as health cash plans.
"Cash plans are better than nothing," explains Debbie Kleiner-Gaines, treasurer of the Association of Medical Insurance Intermediaries. "What they do is get the employee seen faster by a consultant and have MRI scans. It won't go any further than that.
"With PMI, employers will offer it to certain levels of employee - but even if you do offer it to everyone, there's still the job qualifying period."
"I have a client with a PA who has been there for three months and has discovered she has cancer. But she is not eligible for PMI. One way for employers is to offer staff the option of going onto their PMI scheme immediately they join. This avoids this type of situation."
There is also the option of offering PMI for cancer care as part of a flexible benefits scheme, yet Kleiner-Gaines warns there are pitfalls here too: "There is a choice of different benefits, yet the choice the employee goes for may not be health-related: how does that protect the employer or help the employee with cancer?"
She says HR directors considering PMI should avoid going direct to the insurer rather than using a specialist intermediary.
"That doesn't help anyone. They're not getting a better deal. Or independent advice on how well they're covered," she explains.
But what about the preventative methods, such as health screening?
"It is certainly an option in terms of the wider remit of the employer's role," says Ratnarajah. "And in an environment where money is tight, it makes sense, if you are going to generate data, that you benchmark your results against the relevant peer group, either geographical or sector."
James Glover, director at cash plan provider, Simplyhealth, says employers who consider screening and PMI too expensive should look more carefully at cash plans, simply because they do fill in the gaps, with up to £500-worth of consultant fee and diagnosis.
"The problem is often they overlook the benefit of the cash plan for cancer patients because they're focused on the dental or optical benefits. But immediate access to a consultant is very valuable. And there are also compensatory benefits such as post-treatment complementary therapies that can be available via a cash plan," he says.
Even when the nightmare that is cancer is over for staff, employers need to think more proactively about how they manage these employees back into the workplace, as Fergus Craig, Axa PPP commercial director, explains.
He says: "Thankfully, there's a much larger number of people coming back after treatment, who will need reintegrating. Before, you either recovered or you were dead. Now you're more likely to come out recovered, but having been off for a longer period of time."
How my employer handled my cancer
Danae Kindness, people and change consultant at PwC, discovered she had breast cancer in 2006, two years after joining the company.
She needed a mastectomy and reconstructive surgery, which meant she was off work for 10 months.
Now fully recovered, she says her employer gave every possible support throughout her illness.
"Having PMI is one of the great benefits of being in the firm," she says. "I would have had to wait at least three weeks to see a consultant otherwise. But I saw him in a matter of days: a big difference to my state of mind.
"With cancer, having PMI made a difference, both to the shorter diagnosis time and the conversations with the consultant, where we had time to talk. Time pressures on the NHS would have made these conversations much shorter.
"But foremost in my mind when I got the diagnosis was breaking the news to my team leader and colleagues. I am quite an open, straightforward person. Everyone at work was shocked, but very supportive and positive; there was no question about not delivering for clients. Immediately after the operation, my team leader and other colleagues visited me in hospital: that sends a really great message."
"After surgery, I was told I needed 16 weeks of chemotherapy and four weeks of radiotherapy treatment. Through this time, my team leader was in touch regularly and I was allocated an external occupational health adviser to discuss my return to work.
"I went back to work on a phased basis, for three days a week, starting with a half day, followed by a full day and then another half day per week for a month.
"It was exhausting, but my colleagues were brilliant. They were mindful not to put me into demanding situations. I did go through a small crisis of confidence a couple of months after going back, but PwC managed that incredibly well. And it was a short blip.
"Everyone deals with cancer differently and bosses need to take the lead from the individual going through it."
Sarah Churchman, head of engagement and diversity at PwC, explains: "Everyone at PwC is eligible for our private medical scheme and our administrators provide cancer care support.
"Cancer is physical. But we should not underestimate the related psychological aspects. Often, people just want to speak to someone with the same type of cancer as them. We try to be more proactive. It's the psychological support we need to be more conscious of."
Cancer in the UK
Here is a list of the 10 most common cancers among the UK working population (in brackets, diagnoses per year)
Breast (47,693)
Lung (40,806)
Colorectal (39,991)
Prostate (37,051)
Non-Hodgkin's lymphoma (11,861)
Malignant melanoma (11,767)
Bladder (10,335)
Kidney (8,757)
Oesophagus (8,173)
Pancreas (8,085)
Source: Cancer Research UK