That is a little scary but I'm sure there is much more to this. A good study would include finding out how long each has lived there, where they came from, what exposures they had before arrival, and where they spend time when not in the office.
There are three guys out of 150 in my office that had TC. That's 1 in 50. The overall national average is something like 1 per 280. I got mine 5 years after moving to Rhode Island. But I'd spent 49 years in New Jersey, Connecticut, Texas and Virginia, plus I've spent time in 30 other states and 34 countries. One of the other guys, a Brit, was diagnosed 15 years ago in the UK. The third was diagnosed a year after getting here after living 45 years in the Mid-West, primarily the Chicago area.
If you think there is something about your office that has caused the cluster, get your company to start an investigation. Who know? It could be some combination of stress and environmental.
"Statistics are human beings with the tears wiped off" - Paul Brodeur
Diagnosis: 05Sept07 Right I/O: 13Sept07; Pure Seminoma; Surveillance only per NCCN: All Clear February2013 (Chest Xray, Markers); Next check August2013 (CT Scans, Markers)