Table 1. Risk of invasive breast cancer among 2645 female 5-year survivors (32 731 person-years) of Hodgkin's lymphoma diagnosed before age 35 years, initially treated with radiotherapy, and reported to the SEER-9 Programme, 1973–2005.
| BC characteristics | Obs. | SIR | (95% CI) | RRa | (95% CI) | P RR |
|---|---|---|---|---|---|---|
| Total | 166 | 6.13 | (5.23–7.13) | NA | NA | NA |
| Attained age (years) | ||||||
| <35 | 33 | 15.54 | (10.70–21.83) | 1.00 | NA | |
| 35–44 | 82 | 6.68 | (5.31–8.29) | 0.70 | (0.47–1.08) | 0.10 |
| ⩾45 | 51 | 4.02 | (2.99–5.28) | 0.66 | (0.40–1.09) | 0.10 |
| Attained calendar year | ||||||
| 1978–1989 | 11 | 4.69 | (2.34–8.40) | 1.00 | NA | |
| 1990–2005 | 155 | 6.26 | (5.32–7.33) | 1.05 | (0.59–2.06) | >0.5 |
| Histology b | ||||||
| Ductal adenocarcinoma | 131 | 6.45 | (5.39–7.65) | 1.00 | NA | |
| Lobular carcinoma | 9 | 5.47 | (2.50–10.39) | 1.00 | (0.47–1.86) | >0.5 |
| Medullary carcinoma | 7 | 15.49 | (6.23–31.92) | 2.17 | (0.91–4.32) | 0.08 |
| Other or not specified | 19 | 4.06 | (2.44–6.34) | 0.65 | (0.39–1.03) | 0.07 |
| Site c | ||||||
| Upper outer quadrant | 82 | 8.30 | (6.60–10.31) | 1.00 | NA | |
| Lower outer quadrant | 10 | 5.78 | (2.77–10.63) | 0.70 | (0.34–1.28) | 0.26 |
| Upper inner quadrant | 5 | 1.96 | (0.64–4.56) | 0.24 | (0.08–0.53) | <0.001 |
| Lower inner quadrant | 8 | 6.32 | (2.73–12.46) | 0.79 | (0.35–1.54) | >0.5 |
| Central/nipple | 8 | 5.43 | (2.34–10.70) | 0.68 | (0.30–1.31) | 0.27 |
| Overlapping | 30 | 5.50 | (3.71–7.86) | 0.66 | (0.43–1.00) | 0.048 |
| Not specified | 23 | 4.85 | (3.07–7.27) | 0.58 | (0.36–0.91) | 0.02 |
| Laterality | ||||||
| Right | 84 | 6.28 | (5.01–7.77) | 1.00 | NA | |
| Left | 82 | 6.04 | (4.81–7.50) | 0.96 | (0.71–1.31) | >0.5 |
| Stage | ||||||
| Localised | 97 | 6.31 | (5.12–7.70) | 1.00 | NA | |
| Regional | 58 | 5.89 | (4.47–7.61) | 0.87 | (0.62–1.20) | 0.39 |
| Distant | 8 | 5.84 | (2.52–11.50) | 0.88 | (0.39–1.70) | >0.5 |
| Not specified | 3 | 6.07 | (1.25–17.74) | 0.84 | (0.21–2.24) | >0.5 |
| Limited to breast cancer cases diagnosed 1990–2005 d | ||||||
| Tumour size and LNe | ||||||
| ⩽2 cm and LN negative | 63 | 6.40 | (4.92–8.19) | 1.00 | NA | |
| >2 cm and LN negative | 16 | 4.62 | (2.64–7.51) | 0.66 | (0.37–1.11) | 0.12 |
| ⩽2 cm and LN positive | 24 | 6.62 | (4.24–9.85) | 0.96 | (0.59–1.52) | >0.50 |
| >2 cm and LN positive | 25 | 5.50 | (3.56–8.12) | 0.76 | (0.47–1.20) | 0.24 |
| Gradef | ||||||
| Low | 57 | 5.02 | (3.80–6.51) | 1.00 | NA | |
| High | 75 | 7.33 | (5.77–9.19) | 1.26 | (0.89–1.80) | 0.19 |
| Not specified | 23 | 7.25 | (4.60–10.89) | 1.34 | (0.81–2.16) | 0.25 |
| ER/PR | ||||||
| Positive/positive | 63 | 4.96 | (3.81–6.35) | 1.00 | NA | |
| Positive/negative | 12 | 6.23 | (3.22–10.88) | 1.24 | (0.64–2.22) | >0.50 |
| Negative/positive | 1 | 1.31 | (0.03–7.30) | 0.24 | (0.01–1.10) | 0.07 |
| Negative/negative | 51 | 9.31 | (6.93–12.25) | 1.66 | (1.14–2.41) | 0.008 |
| Other and unspecifiedg | 28 | 7.21 | (4.79–10.43) | 1.38 | (0.87–2.13) | 0.17 |
Abbreviations: BC=breast cancer; CI=confidence interval (exact); ER=oestrogen receptor; HL=Hodgkin's lymphoma; LN=lymph nodes; NA=not applicable; Obs=observed number of breast cancers; PR=progesterone receptor; RR=relative risk; SEER=Surveillance, Epidemiology and End Results; SIR=standardised incidence ratio.
Attained calendar year and attained age are adjusted for age at HL diagnosis. All other analyses are adjusted for age at HL and time since HL diagnosis.
Ductal adenocarcinoma includes International Classification of Diseases for Oncology, third edition (ICD-O-3) morphology codes M8500 and M8501, lobular carcinoma includes M8520 and M8521, and medullary carcinoma includes M8510–8512.
ICD-O-3 topography codes include upper outer quadrant (C504, C506), lower outer quadrant (C505), upper inner quadrant (C502), lower inner quadrant (C503), central/nipple (C500–501), overlapping (C508), and not specified (C509).
Includes 2549 female 5-year survivors of HL initially treated with radiotherapy who developed subsequent breast cancer (Obs.=155).
Limited to localised and regional stage disease. Excludes 27 women with distant or unknown stage (n=10) and localised or regional stage disease without known tumour size and/or lymph node involvement (n=17).
Grade was considered in three categories: low (grades I and II), high (grades III and IV) and unspecified.
Includes ‘testing not done’, ‘borderline’ and ‘unknown’ ER and/or PR status.