Cancer odds

[Uglyowl]

Here is the situation.

I work in an office with 75 people who have pretty much all been there for the past 7 years.

Average age: 40
Odds of getting cancer between birth and 40: 1 in 60 get cancer before the age of 40.
We have had 4 confirmed cases of cancer (all under the age of 40) in our office in the past 5 years with 2 more being looked at a possibilities.

Assuming each year there is an equal chance to get cancer what are the odds of having 4 people, 5 people, 6 people get
cancer in a 5 year period.

What is the expected rate?

Thanks!