My husband was the one being examined, as I'm the sponsor and he's the applicant. However, I did find this regarding breast exams in medical exams:
https://www.canada.ca/content/dam/ircc/migration/ircc/english/department/partner/pp/pdf/imei_breast_exam.pdf
Standard procedure seems to be that they do the basic exam the same for everyone - or at least they should - and follow up on anything abnormal.
For example, my husband's urine sample led them to order a follow up 2 hour blood glucose test back home (required, not optional) to rule out diabetes. Even if he had diabetes (he doesn't), that would not have made him inadmissible, but they made it sound like CIC required the follow up test anyway.
Again, no idea if a breast exam is standard procedure. The link above seems to indicate that it isn't. I don't see why it would be, and I would certainly question whether or not it was necessary.