Would 6 ct scans early in your 40s increase your cancer risk later in life? if so by how much and how many years later?

Yes: It depends on the type of ct scan. For standard abd/pelvis Ct scan, 6 scans would result in a total effective dose of 84 mSv, resulting in a theoretical increased lifetime cancer risk of 0.559% or 1/179 over baseline. You can calculate this, and more, at xrayrisk.com . Latency for radiation induced cancer is probably at least 15-20 years.