Last updated: October 9, 2026
Your pack-years do not go down when you quit — they are a record of past exposure. What changes is your risk: it falls steadily the longer you stay smoke-free. Whether you still qualify for lung cancer screening depends on which guideline is used: USPSTF and Medicare stop at 15 years since quitting, while the American Cancer Society (2023) no longer has a quit-date limit.
| USPSTF (2021) | Medicare / CMS (2022) | American Cancer Society (2023) | |
|---|---|---|---|
| Age | 50–80 | 50–77 | 50–80 |
| Pack-years | 20+ | 20+ | 20+ |
| Former smokers | quit within 15 years | quit within 15 years | no limit on years since quitting |
Example: you are 66, smoked a pack a day for 30 years (30 pack-years) and quit 18 years ago. You no longer meet USPSTF or Medicare criteria, but you do meet the American Cancer Society guideline. Ask your doctor which rules your insurer follows.
In Germany the statutory programme requires the quit date to be less than 10 years ago (plus 15+ pack-years and 25+ smoking years, age 50–75): German rules.
Relative risk of former smokers compared with never-smokers (= 1), by years since quitting. SYNERGY pooled analysis, 13,169 cases.
| Quit | Men | Women |
|---|---|---|
| 2–5 years ago | 18× | 6.7× |
| 6–10 years ago | 11× | 4.0× |
| 11–15 years ago | 7.8× | 3.3× |
| 16–25 years ago | 5.1× | 2.0× |
| 26–35 years ago | 2.9× | 1.0× |
| More than 35 years ago | 2.2× | 1.3× |
The drop is large: men who quit 16–25 years earlier had less than a third of the relative risk of men who quit 2–5 years earlier. Risk keeps falling for decades but, for heavy smokers, does not fully return to never-smoker levels — one reason the American Cancer Society removed the 15-year cut-off.
Source: Pesch B et al. Int J Cancer 2012. Full text (PMC)
Thinking about quitting? Free help in the U.S.: smokefree.gov or call 1-800-QUIT-NOW.
No. Pack-years measure cumulative past exposure and stay the same after quitting. Lung cancer risk, however, decreases the longer you remain smoke-free.
Under USPSTF and Medicare rules, no. Under the 2023 American Cancer Society guideline, yes, if you are 50–80 with 20 or more pack-years.
Risk starts falling within the first years and keeps declining for decades. In a large European analysis, men who quit 16–25 years earlier had about 5 times the risk of never-smokers, compared with 18 times for those who quit 2–5 years earlier.
Medicare covers annual low-dose CT for people aged 50–77 with at least 20 pack-years who currently smoke or quit within the last 15 years, after a shared decision-making visit.
Medical disclaimer: This page is for information only and is not medical advice. Talk to a qualified healthcare professional about your own situation.