Table 1.
A list of the literature reporting the incidence, risk, and survival of radiation-associated rectal cancer compared to non-irradiated patients [located below citations].
| Study | Data Source | Cohort Size * | Latency Period Inclusion |
Follow-Up Duration | Radiation Modality | Control Group | Analysis | Findings ** |
|---|---|---|---|---|---|---|---|---|
| Neugut et al. (1997) [20] | SEER | 141,761 | ≥6 mo | Not reported † |
Not reported |
RT− | Time from treatment | |
| 6 mo < 5 yrs | RT+: RR 0.7 (0.5–0.9) RT−: RR 0.8 (0.7–0.9) |
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| 5–8 yrs | RT+: RR 0.8 (0.5–1.2) RT−: RR 0.8 (0.6–1.0) |
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| >8 yrs | RT+: RR 0.8 (0.4–1.3) RT−: RR 0.8 (0.6–1.1) |
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| Brenner et al. (2000) [21] | SEER | 122,123 | ≥2 mo | ≥10 yrs | Not reported |
Sx | Time from treatment | |
| ≥5 yrs | 35% increased risk (95% CI, −1, 86); p = 0.06 | |||||||
| ≥10 yrs | 105% increased risk (95% CI, 9, 292); p = 0.03 | |||||||
| Baxter et al. (2005) [22] | SEER | 85,815 | ≥5 yrs | Mean >9 yrs |
EBRT | Sx | Definitely irradiated sites Potentially irradiated sites Non-irradiated sites |
HR 1.70 (95% CI: 1.4–2.2); p < 0.0001 HR 1.08 (95% CI: 0.92–1.26); p = 0.35 HR 0.95 (95% CI: 0.78–1.15); p = 0.58 |
| RT+ vs. RT−: 70% increase in the development of RARC | ||||||||
| Neider et al. (2005) [18] | SEER | 243,082 | ≥6 mo | >10 yrs | EBRT BT EBRT-BT |
Sx | Time from treatment Entire follow-up period |
EBRT: HR 1.26 (95% CI: 1.08, 1.47) BT: HR 1.08 (95% CI: 0.77, 1.54) EBRT−BT: HR 1.21 (95% CI: 0.89, 1.65) |
| Risks vary depending on RT modality and time | ||||||||
| Kendal et al. (2006) [23] | SEER | 237,773 | ≥5 yrs | Median 5 yrs |
EBRT | Sx WW |
Time from treatment Entire follow-up period |
RT+ vs. Sx: RR 2.38 (95% CI: 2.21–2.55) Sx vs. WW: RR 3.44 (95% CI: 3.22–3.67) |
| The WW group had a higher risk of rectal cancer than RT+ group, suggesting radiation does not influence this process. | ||||||||
| Moon et al. (2006) [17] | SEER | 140,767 | ≥5 yrs | Median 10 yrs |
EBRT | RT− | Time from treatment ≥5 yrs |
EBRT: OR 1.60 (95% CI, 1.29–1.99) |
| BT, either in isolation or in combination with EBRT, did not show significantly different odds of RARC | ||||||||
| Boorjian et al. (2007) [24] | CaPSURE | 9681 | ≥30 days | Median 39 mo |
EBRT BT EBRT-RT |
RT− | Entire follow-up period | RT+: 11/31 patients (35%, p = 0.14) |
| Rapiti et al. (2008) [25] | GCR | 1134 | ≥5 yrs | Median 7.4 yrs |
EBRT | RT− | Time from treatment | |
| 5–9 yrs | RT+: SIR 1.2 (95% CI: 0.04–6.9) RT−: SIR 1.5 (95% CI: 0.4–3.9) |
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| ≥10 yrs | RT+: SIR 5.3 (95% CI: 0.2–29.3) RT−: undefined |
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| Increased incidence of colon cancer in 13 patients | ||||||||
| Huo et al. (2009) [26] | SEER | 635,910 | Notreported | >10 yrs | EBRT BT |
RT− | Time from treatment | |
| <6 mo (p = 0.02) | RT+: SIR 0.99 (95% CI: 0.77–1.27) RT−: SIR 1.38 (95% CI: 1.19–1.60) |
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| 6 mo–5 yrs (p = 0.95) | RT+: SIR 0.96 (95% CI: 0.88–1.05) RT−: SIR 0.96 (95% CI: 0.90–1.02) |
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| >5–10 yrs (p = 0.08) | RT+: SIR 1.06 (95% CI: 0.93–1.20) RT−: SIR 0.92 (95% CI: 0.84–1.01) |
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| >10 yrs (p < 0.0001) | RT+: SIR 1.44 (95% CI: 1.22–1.71) RT−: SIR 0.76 (95% CI: 0.65–0.88) |
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| Entire follow-up period (p = 0.03) |
RT+: RR 1.04 (95% CI: 0.97–1.11) RT−: RR 0.95 (95% CI: 0.91–1.00) |
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| Hinnen et al. (2011) [27] | NCR | 1888 | ≥1 yr | Median 7.5 yrs |
BT | Sx | Time from treatment | |
| 1–4 yrs | BT: RR 0.41 (95% CI: 0.05–1.48) RP: RR 2.12 (95% CI: 0.69–4.94) |
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| 5–15 yrs | BT: RR 1.78 (95% CI: 0.71–3.67) RP: RR 0.96 (95% CI:0.19–2.81) |
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| Joung et al. (2015) [28] | KCR | 55,378 | >2 mo | Median 3.5 yrs |
Not reported |
RT− | Time from treatment | RT+: SIR 1.03 (CI not reported) RT−: SIR 0.67 (CI not reported), p < 0.05 |
| Rombouts et al. (2020) [29] | NCR | 96,577 | Not reported |
Median 6.8 yrs |
Not reported |
RT− | Time from treatment | RT+: SIR 1.20 (95% CI: 1.10–1.30) RT−: SIR 0.99 (95% CI: 0.91–1.06) |
| Subhazard ratio Crude incidence ratio |
SHR: 1.89 (95% CI: 1.66–2.16) CIR: 1.3% RT+ vs. 0.7% RT− (p < 0.001) |
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| 5-yr overall survival |
RT+: 33.7% (95% CI: 29.6–37.8) RT−: 39.1% (95% CI: 35.4–42.8) |
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| Yang et al. (2020) [19] | SEER | 291,395 | ≤5 yrs | >20 yrs | EBRT BT EBRT-BT |
RT− | Time from treatment | |
| Entire follow-up period | RT+, EBRT: SIR 1.22 (95% CI: 1.09–1.36) RT+, EBRT−BT: SIR 1.85 (95% CI: 1.60–2.14) RT−: SIR 0.85 (95% CI: 0.8–0.91) |
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| 5-yr OS | Significantly lower in RT−SPRC vs. matched-PRCO group HR = 1.33 (95% CI: 1.14–1.55); p < 0.001 |
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| 5-yr RCSS | Significantly lower in RT−SPRC vs. matched-PRCO group HR = 1.30 (95% CI: 1.07–1.58); p = 0.004 |
* Cohort size. ** Risks, incidences and outcomes of rectal cancer. † Not reported: not explicitly stated by the authors. Sx: treated with surgery. RT+: treated with radiation. RT−: treated without radiation. WW: prostate cancer group undergoing active surveillance. OS: overall survival. RCSS: rectal cancer-specific survival. SEER: Surveillance, Epidemiology, and End Results Cancer Registry. NCR: Netherlands Cancer Registry. CaPSURE: Cancer of the Prostate Strategic Urologic Research Endeavor. GCR: Geneva Cancer Registry. KCR: Korean Cancer Registry. RT-SPRC: second primary rectal cancer after radiotherapy (≈RARC). PRCO: primary rectal cancer only (≈rectal cancer without previous pelvic cancer). EBRT: external beam radiation therapy. BT: brachytherapy. RP: radical prostatectomy. HR: hazard ratio. OR: odds ratio. CI: confidence interval. Mo: months. yr: year. yrs: years.