"I don't think about it," he says. "It's never figured in the way I think about what I do. Diversity is an important issue, but my colour is not an issue for me or the organisation."
Kumar is also the first person to lead the UK's biggest charity who is not a scientist or clinician. "It's become such a big job that it's hard to be chief executive and work in a lab," he says. "There are a number of different dimensions to the position - you have to think about advocacy and fundraising as well as the scientific background."
Kumar officially takes over the role on 2 April and is currently the chief executive of the charity's subsidiary development company, Cancer Research Technology, the income of which has trebled under his tenure.
But he insists his appointment does not signal a change of direction for CRUK. "There aren't going to be any radical changes," says Kumar. "I work closely with our current chief executive, Alex Markham, and have been part of the decision-making processes that have helped get us where we are today.
"The major initiatives are ones we have been working on for some time now - we are expanding our programme of research and looking at how we can extend the reach of what we do across the whole of the UK.
"We already have activity throughout the country, and we want to strengthen that. The more research we do in different locations, the more impact that has on improving outcomes for cancer patients, which is ultimately what we are about."
Given that CRUK is already the most financially successful charity in the country - its annual income is in the region of £344m - it is unsurprising that there are no plans for a radical overhaul - if it ain't broke, don't fix it. So how can the charity maintain pole position?
"We are raising our profile in advocacy in order to keep cancer at the top of the political agenda," says Kumar. "With an ageing population, the incidence of cancer is going to increase. The expectation is that there will be 30 per cent more cancer patients by 2020. Cancer patients are a very important voice in this country - one in three people will get cancer in their lifetime - so they're next to impossible for politicians to ignore. It's rapidly becoming our biggest health burden."
Despite CRUK's enviable public profile, Kumar believes there is room for improvement. "We are making progress, but we haven't always been as good as we could be in conveying that progress and impact," he says.
"We are trying to get better at it, and I think all charities need to do the same."
In the past, CRUK's success has led to accusations that it is squeezing smaller charities out of the market. Neil Brookes, chief executive of Bowel Cancer UK, has even compared CRUK to Tesco. But Kumar rejects this line of argument.
"I don't subscribe to the view that if we increase our income we are taking it away from other charities," he says. "If we all become more effective at demonstrating our impact, there's no reason to believe the public won't be more generous. However, based on our own feedback, I think the public would say there are too many cancer charities. But that's not for us to say."
Kumar believes that one way to avoid repetition and waste is by working in partnership. "We don't see ourselves working in isolation," he says. "In a sense, everything we do is a partnership, and people will start to see more public evidence of that."
2007 - Chief executive, Cancer Research UK
2004 - Chief operating officer, Cancer Research UK
2002 - Chief executive, Cancer Research Technology
1997 - Chief executive, Nexan Group
1993 - Chief executive, Papworth Trust