Table 5.
Association of age and number of positive LNs in node-positive patients*
| Age at diagnosis, y | No. | No. Pos LNs | Estimates from Poisson regression models† | ||||
|---|---|---|---|---|---|---|---|
| Mean | SD | RR‡ (95% CI) | P§ | ||||
| T1: stratification by number of LNE | |||||||
| <12 LNs examined (n = 605) | .98 | ||||||
| 20–39 | 19 | 1.58 | 1.02 | 0.95 (0.71 to 1.25) | |||
| 40–49 | 59 | 1.75 | 1.36 | 1.06 (0.87 to 1.29) | |||
| 50–59 | 13 | 1.68 | 1.27 | 1.00 (0.86 to 1.17) | |||
| 60–69 | 173 | 1.69 | 1.18 | 1 (Ref) | |||
| 70–79 | 156 | 1.66 | 1.04 | 1.01 (0.88 to 1.16) | |||
| 80+ | 68 | 1.62 | 0.90 | 0.97 (0.83 to 1.14) | |||
| 12+ LNs examined (n = 384) | .026 | ||||||
| 20–39 | 25 | 3.96 | 4.05 | 1.40 (0.87 to 2.25) | |||
| 40–49 | 55 | 2.31 | 1.96 | 0.82 (0.58 to 1.18) | |||
| 50–59 | 108 | 2.70 | 2.95 | 1.00 (0.72 to 1.39) | |||
| 60–69 | 95 | 2.83 | 3.85 | 1 (Ref) | |||
| 70–79 | 72 | 1.85 | 1.62 | 0.65 (0.46 to 0.94) | |||
| 80+ | 29 | 2.86 | 3.53 | 1.00 (0.59 to 1.71) | |||
| T2: no stratification (n = 3257) | .042 | ||||||
| 20–39 | 93 | 3.44 | 2.91 | 1.13 (0.95 to 1.34) | |||
| 40–49 | 293 | 3.11 | 2.96 | 1.09 (0.97 to 1.23) | |||
| 50–59 | 653 | 2.72 | 2.64 | 1.01 (0.92 to 1.10) | |||
| 60–69 | 896 | 2.57 | 2.41 | 1 (Ref) | |||
| 70–79 | 868 | 2.44 | 2.35 | 0.94 (0.87 to 1.03) | |||
| 80+ | 448 | 2.26 | 2.50 | 0.89 (0.79 to 1.00) | |||
| T3: stratification by type of surgery | |||||||
| APR surgery (n = 3102) | .079 | ||||||
| 20–39 | 57 | 7.98 | 9.28 | 1.41 (1.11 to 1.80) | |||
| 40–49 | 223 | 5.04 | 5.40 | 1.02 (0.89 to 1.16) | |||
| 50–59 | 522 | 5.10 | 4.93 | 1.12 (1.01 to 1.23) | |||
| 60–69 | 830 | 4.23 | 4.33 | 1 (Ref) | |||
| 70–79 | 964 | 4.44 | 5.11 | 1.08 (0.98 to 1.18) | |||
| 80+ | 506 | 4.31 | 4.47 | 1.03 (0.93 to 1.15) | |||
| EBR/exenter surgery (n = 625) | .76 | ||||||
| 20–39 | 46 | 5.46 | 4.68 | 0.94 (0.64 to 1.38) | |||
| 40–49 | 79 | 4.52 | 5.33 | 0.91 (0.65 to 1.27 | |||
| 50–59 | 105 | 4.31 | 5.58 | 0.94 (0.67 to 1.31) | |||
| 60–69 | 135 | 4.34 | 8.11 | 1 (Ref) | |||
| 70–79 | 168 | 3.63 | 3.24 | 0.92 (0.72 to 1.18) | |||
| 80+ | 92 | 4.36 | 4.84 | 1.12 (0.83 to 1.51) | |||
| Upper resection surgery (n = 11 710) | <.0001 | ||||||
| 20–39 | 311 | 5.11 | 4.44 | 1.00 (0.91 to 1.11) | |||
| 40–49 | 1079 | 4.87 | 4.83 | 1.11 (1.04 to 1.18) | |||
| 50–59 | 2281 | 4.28 | 4.36 | 1.01 (0.96 to 1.06) | |||
| 60–69 | 2939 | 4.08 | 4.21 | 1 (Ref) | |||
| 70–79 | 3158 | 3.86 | 4.05 | 0.98 (0.93 to 1.03) | |||
| 80+ | 1942 | 3.56 | 3.73 | 0.92 (0.87 to 0.97) | |||
| T4: no stratification (n = 1168) | .23 | ||||||
| 20–39 | 38 | 7.05 | 5.69 | 1.25 (0.97 to 1.61) | |||
| 40–49 | 113 | 4.65 | 4.38 | 0.98 (0.80 to 1.21) | |||
| 50–59 | 213 | 4.76 | 5.04 | 0.99 (0.83 to 1.17) | |||
| 60–69 | 276 | 4.33 | 4.48 | 1 (Ref) | |||
| 70–79 | 299 | 4.47 | 4.39 | 1.03 (0.89 to 1.20) | |||
| 80+ | 229 | 4.76 | 4.25 | 1.15 (0.99 to 1.34) | |||
* Statistically significant interactions with age required further stratification by number of lymph nodes examined (T1 only) and by type of surgery (T3 only). CI = confidence interval; LNE = No. lymph nodes examined; Ref = referent; RR = rate ratio.
† Covariates include log (number of lymph nodes examined), year of diagnosis (categorical variable in 3-year intervals), grade (I, II, III/IV/unknown), sex, race (3 categories: white, black, other). Surgery (APR, EBR/exent, upper resection) included for stages T1, T2, and T4.
‡ Rate ratio compares mean number of positive LNs for each age group relative to the reference group (age 60–65 years) after adjusting for covariates.
§ P value corresponds to the Score statistic Chi-square test for the age variable in the multivariable model after adjusting for other covariates. All statistical tests were two-sided.