Table 1.
Risk of cancer with 1-, 2-, and ≥3 dispensings of gabapentin versus no dispensing in KPNC
| Cancer Site (alphabetical after “Any Cancer”) | GP exposed cases (N) | OR (95%CI) and p-value for 1-, 2-, and ≥3 dispensings of gabapentin versus no dispensings (2-year lag) | ||
|---|---|---|---|---|
| 1 dispensing vs none | 2 dispensings vs none | ≥3 dispensings vs none | ||
| Any Cancer | 1678 | 1.05 (0.96–1.14) p=0.276 | 1.20 (1.06–1.36) p=0.005 | 1.10 (1.02–1.18) p=0.009** |
| Anus/anal canal/Anorectum | 9 | 0.41 (0.06–3.03) p=0.382 | 1.42 (0.17–11.52) p=0.744 | 2.70 (1.17–6.25) p=0.021* |
| Biliary | 7 | Inestimable | 3.35 (1.06–10.57) p=0.040 | 0.81 (0.25–2.63) p=0.726 |
| Bones/joints | 4 | 4.30 (1.11–16.62) p=0.035 | Inestimable | 1.29 (0.16–10.30) p=0.812 |
| Brain | 21 | 1.84 (0.93–3.65) p=0.079 | 0.87 (0.20–3.73) p=0.851 | 1.16 (0.58–2.32) p=0.673 |
| Breast | 352 | 1.09 (0.90–1.31) p=0.375 | 1.35 (1.03–1.78) p=0.032 | 1.19 (1.01–1.39) p=0.038* |
| Cervix uteri | 6 | 0.60 (0.14–2.50) p=0.481 | 1.41 (0.32–6.22) p=0.647 | 0.49 (0.12–2.01) p=0.320 |
| Colon excl. Rectum | 145 | 1.13 (0.85–1.50) p=0.391 | 1.13 (0.73–1.74) p=0.586 | 0.96 (0.75–1.24) p=0.768 |
| Comb mouth-pharynx1 | 9 | 0.91 (0.28–2.96) p=0.874 | Inestimable | 1.14 (0.49–2.68) p=0.760 |
| Corpus uteri | 36 | 0.39 (0.20–0.76) p=0.006 | 0.60 (0.28–1.29) p=0.189 | 0.64 (0.40–1.00) p=0.052 |
| Esophagus | 17 | 0.82 (0.30–2.28) p=0.707 | 2.67 (0.89–8.05) p=0.081 | 1.24 (0.62–2.48) p=0.550 |
| Eye and orbit | 0 | Inestimable | Inestimable | Inestimable |
| Gallbladder | 3 | 1.84 (0.40–8.46) p=0.433 | Inestimable | 0.55 (0.07–4.17) p=0.563 |
| Heart/soft tissue | 12 | 1.19 (0.42–3.38) p=0.748 | 2.31 (0.66–8.12) p=0.190 | 0.99 (0.39–2.48) p=0.978 |
| Hodgkin lymphoma | 10 | 1.93 (0.66–5.63) p=0.228 | 2.95 (0.61–14.19) p=0.178 | 1.96 (0.67–5.75) p=0.222 |
| Kidney/renal pelvis | 70 | 1.20 (0.75–1.94) p=0.450 | 2.48 (1.46–4.24) p=0.001 | 1.71 (1.18–2.47) p=0.004* |
| Larynx | 10 | 1.35 (0.53–3.46) p=0.531 | 2.71 (0.76–9.72) p=0.126 | 0.49 (0.12–2.05) p=0.331 |
| Lip | 8 | 1.11 (0.39–3.15) p=0.841 | 0.67 (0.09–5.08) p=0.695 | 1.11 (0.34–3.69) p=0.861 |
| Liver/intrahep.bile duct | 36 | 2.19 (1.29–3.72) p=0.004 | 0.69 (0.17–2.90) p=0.614 | 1.65 (0.98–2.77) p=0.058 |
| Lung and bronchus | 269 | 0.87 (0.68–1.11) p=0.250 | 1.50 (1.11–2.02) p=0.008 | 1.34 (1.13–1.60) p=0.001** |
| Lymphocytic leukemia | 19 | 1.48 (0.67–3.29) p=0.337 | 1.68 (0.58–4.85) p=0.335 | 1.14 (0.55–2.39) p=0.727 |
| Melanoma | 73 | 0.97 (0.63–1.51) p=0.896 | 1.15 (0.62–2.14) p=0.665 | 1.11 (0.80–1.54) p=0.534 |
| Monocytic leukemia | 0 | Inestimable | Inestimable | Inestimable |
| Multiple myeloma | 27 | 1.46 (0.81–2.63) p=0.211 | 0.32 (0.04–2.30) p=0.255 | 1.11 (0.62–1.97) p=0.730 |
| Myeloid leukemia | 16 | 0.48 (0.15–1.53) p=0.216 | 0.54 (0.13–2.26) p=0.399 | 1.64 (0.86–3.12) p=0.134 |
| Nasopharynx | 0 | Inestimable | Inestimable | Inestimable |
| Non-hodgkin lymphoma | 87 | 1.17 (0.82–1.69) p=0.391 | 1.06 (0.57–1.98) p=0.848 | 1.16 (0.85–1.60) p=0.356 |
| Nose/nasal cavity/middle ear | 2 | 1.01 (0.13–7.88) p=0.994 | Inestimable | 1.43 (0.18–11.62) p=0.739 |
| Other digestive organs | 6 | 2.86 (0.59–13.75) p=0.190 | 6.67 (1.11–39.90) p=0.038 | 4.33 (0.78–24.07) p=0.094 |
| Other endocrine | 1 | Inestimable | Inestimable | 2.50 (0.28–22.37) p=0.413 |
| Other female genital | 1 | Inestimable | Inestimable | 1.24 (0.15–9.88) p=0.842 |
| Other leukemia | 3 | Inestimable | Inestimable | 1.86 (0.54–6.44) p=0.33 |
| Other male genital | 1 | 3.33 (0.35–32.05) p=0.297 | Inestimable | Inestimable |
| Other nervous system | 2 | Inestimable | Inestimable | 6.67 (1.11–39.90) p=0.038* |
| Other skin | 11 | 2.29 (0.92–5.66) p=0.074 | Inestimable | 1.49 (0.57–3.85) p=0.416 |
| Other urinary | 1 | Inestimable | Inestimable | Inestimable |
| Ovary | 23 | 0.94 (0.49–1.80) p=0.849 | 0.62 (0.19–2.00) p=0.426 | 0.77 (0.40–1.46) p=0.417 |
| Pancreas | 46 | 0.74 (0.41–1.34) p=0.318 | 0.24 (0.06–0.96) p=0.043 | 1.23 (0.85–1.78) p=0.282 |
| Penis | 3 | Inestimable | Inestimable | 6.68 (1.47–30.28) p=0.014* |
| Peritoneum/Omentum/Mesentery | 7 | 2.86 (0.76–10.7) p=0.119 | Inestimable | 1.68 (0.58–4.91) p=0.341 |
| Pleura | 1 | Inestimable | Inestimable | Inestimable |
| Prostate | 246 | 1.10 (0.89–1.36) p=0.379 | 1.03 (0.74–1.43) p=0.855 | 0.78 (0.64–0.94) p=0.011† |
| Rectum/Rectosigmoid | 30 | 0.70 (0.39–1.26) p=0.236 | 1.03 (0.52–2.06) p=0.925 | 0.41 (0.21–0.80) p=0.009†† |
| Retroperito-neum | 1 | 1.64 (0.19–14.30) p=0.652 | Inestimable | Inestimable |
| Salivary glands | 8 | 2.55 (0.72–9.06) p=0.147 | Inestimable | 1.67 (0.64–4.36) p=0.298 |
| Small intestine | 8 | 0.82 (0.19–3.48) p=0.789 | 3.00 (0.82–10.88) p=0.096 | 2.05 (0.58–7.33) p=0.268 |
| Stomach | 27 | 0.65 (0.30–1.41) p=0.276 | Inestimable | 1.64 (1.01–2.64) p=0.045* |
| Testis | 3 | Inestimable | Inestimable | 1.82 (0.40–8.20) p=0.437 |
| Thyroid | 26 | 1.06 (0.46–2.48) p=0.886 | 2.16 (0.90–5.22) p=0.087 | 1.51 (0.86–2.66) p=0.155 |
| Trachea | 0 | Inestimable | Inestimable | Inestimable |
| Unspecified | 75 | 1.65 (1.12–2.42) p=0.011 | 1.55 (0.86–2.78) p=0.143 | 1.20 (0.82–1.74) p=0.349 |
| Ureter | 4 | 2.02 (0.44–9.22) p=0.366 | 3.40 (0.35–32.69) p=0.290 | 0.74 (0.10–5.68) p=0.771 |
| Urinary bladder | 100 | 1.20 (0.84–1.71) p=0.309 | 0.70 (0.34–1.43) p=0.325 | 1.41 (1.07–1.87) p=0.015* |
| Uterus | 2 | 4.83 (0.44–53.25) p=0.199 | 5.00 (0.45–55.14) p=0.189 | Inestimable |
| Vagina | 3 | 1.70 (0.20–14.12) p=0.624 | Inestimable | 2.49 (0.53–11.73) p=0.249 |
| Vulva | 3 | 0.54 (0.07–4.14) p=0.554 | Inestimable | 1.11 (0.25–4.84) p=0.895 |
KPNC, Kaiser Permanente Northern California; GP, gabapentin; OR, odds ratio; CI, confidence interval; vs, versus; excl, excluding; intrahep, intrahepatic; comb, combined.
Inestimable – no gabapentin-exposed cancer cases or no gabapentin-exposed non-cases at the exposure level, p > 0.97.
1
Excludes lip, salivary glands and nasopharynx
*
p<.05, OR>1 for ≥3 dispensings vs no dispensings
**
p<.01, OR>1 for ≥3 dispensings vs no dispensings
†
p<.05, OR<1 for ≥3 dispensings vs no dispensings
††
p<.01, OR<1 for ≥3 dispensings vs no dispensings