Table 2. Treatment-related risks for stomach cancer among patients with testicular cancer and matched controls.
| Number of cases | Number of controls | Odds ratio | 95% Confidence intervals | |
|---|---|---|---|---|
|
Any radiotherapya | ||||
| No | 4 | 29 | 1 | Ref |
| Yes | 87 | 151 | 5.9 | 1.7–20.7 |
| Unknown | 1 | 0 | Inf | 0.9–Inf |
|
Radiation dose (Gy)a | ||||
| 0–9.9 | 15 | 49 | 1 | Ref |
| 10.0–19.9 | 7 | 16 | 2.0 | 0.5–8.7 |
| 20.0–29.9 | 17 | 43 | 2.5 | 0.8–7.9 |
| 30.0–39.9 | 28 | 39 | 7.2 | 2.1–24.9 |
| 40.0–49.9 | 11 | 21 | 6.7 | 1.7–27.1 |
| ⩾50.0b | 8 | 6 | 20.5 | 3.7–114.3 |
| Unknownc | 6 | 6 | 4.5 | 1.0–21.5 |
| P-trenddEOR per Gy=0.27 (95% CI 0.054–1.44) | <0.001 | |||
|
Any chemotherapye,f | ||||
| No | 77 | 157 | 1 | Ref |
| Yes | 14 | 23 | 1.1 | 0.5–2.5 |
| Unknown | 1 | 0 | ||
|
Cisplatine,g,h | ||||
| None | 84 | 170 | 1 | Ref |
| <500 mg m−2 | 4 | 6 | 1.4 | 0.3–5.6 |
| ⩾500 mg m−2 | 3 | 4 | 1.3 | 0.2–8.2 |
| Unknown | 1 | 0 | ||
| P-trendi | 0.692 | |||
|
Number of chemotherapy cycles including alkylating agentse | ||||
| 0 | 80 | 161 | 1 | Ref |
| 1–4 | 5 | 10 | 0.9 | 0.3–3.0 |
| ⩾5 | 5 | 9 | 1.1 | 0.3–3.8 |
| Unknown | 2 | 1 | ||
| P-trendj | 0.245 | |||
Abbreviations: CI=confidence interval; EOR=excess odds ratio; Gy=gray; Inf=infinity; Ref=reference.
Not adjusted for chemotherapy.
Range: 50–59.1 Gy, median: 50.8 Gy.
For 11 of 12 patients with unknown dose, it was established that they had received radiotherapy. All 12 patients were included in the analysis via a missing dose indicator variable as described in the Materials and Methods section.
Based on continuous (linear) dose.
Adjusted for radiation dose in seven categories specified in the table.
In all, 7 cases and 10 controls received cisplatin, including 1 case and 4 controls who also received etoposide and 1 control who also received doxorubicin; 1 case received ifosfamide, cisplatin and etoposide; 4 cases and 4 controls received cyclophosphamide, including 1 control who also received doxorubicin; 5 controls received exclusively chlorambucil; 3 cases and 4 controls received only antitumour antibiotics other than doxorubicin, epirubicin or mitoxantrone, including 1 case who also received a vinca alkaloid (specific drug not coded).
In all, 6 of the 7 cases and 3 of the 10 controls exposed to cisplatin also received radiotherapy, respectively.
One cycle of chemotherapy often includes 100 mg m−2 cisplatin.
Based on continuous (loglinear) dose.
Based on continuous (loglinear) number of cycles.