Impact of smoking on cancer stage at diagnosis.
BACKGROUND
Studies evaluating the relationship between smoking and cancer spread are limited.


METHODS
We studied the relationship between cancer stage at diagnosis (local, regional, or metastatic) and smoking history (current, previous, or nonsmoker). For lung cancer, patterns of spread were also studied.


RESULTS
In a tumor registry for eastern North Dakota, northwestern Minnesota, and northern South Dakota, 11,716 cases were identified from 1986 to 2001. Current smokers (relative risk [RR], 2.11; 95% confidence interval, 1.93 to 2.32; P <.001) and previous smokers (RR, 1.56; 95% confidence interval, 1.42 to 1.72; P <.001) had an increased risk of metastatic disease at diagnosis. Current smokers (RR, 1.39; 95% confidence interval, 1.29 to 1.51; P <.001), but not previous smokers, also had an increased risk of regional disease. An increase in metastatic disease was most evident for prostate cancer (RR, 1.53; P =.003). An increase in regional disease was most evident for head and neck (RR, 3.53; P <.001), prostate (RR, 1.83; P =.030), and breast cancer (RR, 1.22; P =.005). Compared with previous smokers, current smokers with metastatic lung cancer were more likely to have involvement of the brain (33.6% v 23.0%; P =.004), bone marrow, adrenal gland, and pericardium (24.7% v 15.9%; P =.004).


CONCLUSIONS
Previous or current smoking is a risk factor for increased cancer stage in a wide range of malignancies. Further study is required to determine whether this association is causal.
Kobrinsky
Nathan L
NL
Roger Maris Cancer Center, Fargo, North Dakota, USA. nathankobrinsky@meritcare.com
Klug
Marilyn G
MG
Hokanson
Peggy Jo
PJ
Sjolander
Diane E
DE
Burd
Larry
L
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D009367:Neoplasm Staging; D009369:Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology*; D009658:North Dakota / Q000453:epidemiology; D012042:Registries; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D013023:South Dakota / Q000453:epidemiology