Table 3.

RR (95% CI) for pancreatic cancer according to quartiles of plasma C-peptide in HPFS, NHS, PHS, and WHI cohorts

Cases/controlsQuartiles of serum C-peptide
Ptrend
1 (low)
2
3
4 (high)
46/14440/14136/14375/143
RR (95% CI)
    Matching factors*1.00.86 (0.53-1.41)0.79 (0.48-1.30)1.63 (1.03-2.57)0.002
    Multivariable1.00.82 (0.49-1.38)0.78 (0.45-1.35)1.52 (0.87-2.64)0.005
Excluding cases diagnosed <4 y after blood draw
    Cases/controls29/10330/9127/10751/98
    RR (95% CI)
        Matching factors*1.01.13 (0.63-2.04)0.92 (0.51-1.66)1.79 (1.02-3.13)0.01
        Multivariable1.01.10 (0.59-2.05)0.99 (0.52-1.86)1.90 (0.97-3.73)0.01
  • NOTE: Cohort specific cutpoints (quartiles 1-4): HPFS <1.20, 1.20-1.52, 1.53-2.01, >2.01; NHS <1.08, 1.08-1.44, 1.45-1.98, >1.98; PHS <1.23, 1.23-1.82, 1.83-2.83, >2.83; WHI <0.98, 0.98-1.32, 1.33-1.94, >1.94.

  • * Matching factors include age, month of blood draw, smoking status (never, past, current), cohort, and fasting status.

  • Additionally controlling for BMI (quartiles), physical activity (quartiles), current multivitamin use, high smoking dose (25+ cigarettes/d for HPFS and NHS; 20+ cigarettes/d for PHS), and time between last meal and blood draw.