PGR and cancer: However, an extremely high risk for ER-/PgR- cancer was found for start of smoking at an early age (OR = 7.01, 95%CI: 2.07-23.73 for ≤19 years), although the confidence interval for this category was wide, and the trend test for age at the start of smoking failed to demonstrate any significance (Ptrend = 0.71).