Women ask, "Will this progress to cancer? When?" when they have an abnormal Pap smear. I wish there was a simple answer, but it's a bit complicated.
The reason it's complicated is that unless you have only had intercourse with one person, you don't know when you were infected with HPV. If we knew when you were infected and then later you developed cervical cancer, we would know exactly how long it took.
But we do know that HPV infection can linger for years and cause no damage because some women have repeat Pap smears that show HPV but otherwise normal tissue. Most women who are HPV positive at one time will be HPV negative within a couple of years. As long as their Pap tests are normal, HPV can be watched.
ASCUS, LSIL and HSIL are not cancer, but they aren't normal either. ASCUS is the least scary because it's really the lab saying, "We don't know what this is." ASCUS also can be due to a bad sample or not handling the sample properly, and there's actually nothing wrong with the patient. LSIL is abnormal, but low-grade. HSIL, of course, is high-grade abnormal tissue.
Only about 10% of LSIL cases progresses to cancer, so doctors aren't usually jumping all over to treat that quickly. There are exceptions, like if you're over 30 years old and HPV-positive. In that case, it has probably been incubating for over 10 years already.
High-grade is the most likely to go to cancer at some point. But doctors won't watch and wait. They will want to do treatment now, which is typically a LEEP or cone biopsy. Even though HPV does its damage slowly in most cases, in some it's a bit quicker. Again, the big problem is that we don't know when you were initially infected.
And along the way, your body may take over and put HPV into hibernation and repair any damage on its own if it's not too far along. ASCUS and LSIL are definitely something that your body may repair itself, but HSIL is probably getting too far and requires treatment now.
So while it does takes years to become cancer from when you were first infected with HPV, you still need to get regular Pap smears, and if your doctor recommends a colposcopy and biopsy, follow that advice.