If they knew precisely what caused cervical cancer my guess is that they would put an end to it. But the fact is they don't definitively know what causes cervical cancer, and it's likely many things not just one.
In terms of sexual promiscuity that's a lie, and the only likely link between his conclusion is that all cases of cervical cancer involve HPV, but not all cases of HPV lead to cervical cancer. HPV is a sexually transmitted disease, but it can be transmitted just once and isn't at all indicative of the number of partners someone has had.
Take care, and if you are up to it, you should certainly file a complaint with the American Medical Association against this doctor.