PURPOSE: To analyze the occurrence of subacute and late adverse effects in patients treated with preoperative irradiation for rectal cancer. PATIENTS AND METHODS: The study population included 1,147 patients randomly assigned to preoperative radiation therapy or surgery alone in the Swedish Rectal Cancer Trial conducted 1987 through 1990. Patient data were matched against the Swedish Hospital Discharge Register to identify patients admitted to hospital after the primary treatment of the rectal cancer. Patients with known residual disease were excluded, and patients with a recurrence were censored 3 months before the date of recurrence. Relative risks (RR) with 95% CIs were calculated. RESULTS: Irradiated patients were at increased risk of admissions during the first 6 months from the primary treatment (RR = 1.64; 95% CI, 1.21 to 2.22); these were mainly for gastrointestinal diagnoses. Overall, the two groups showed no difference in the risk of admissions more than 6 months from the primary treatment (RR = 0.95; 95% CI, 0.80 to 1.12). Regarding specific diagnoses, however, RRs were increased for admissions later than 6 months from the primary treatment in irradiated patients for unspecified infections, bowel obstruction, abdominal pain, and nausea. CONCLUSION: Gastrointestinal disorders, resulting in hospital admissions, seem to be the most common adverse effect of short-course preoperative radiation therapy in patients with rectal cancer. Bowel obstruction was the diagnosis of potentially greatest importance, which was more frequent in irradiated than in nonirradiated patients.
The genetic susceptibility to colorectal cancer (CRC) has been estimated to be around 35% and yet high-penetrance germline mutations found so far explain less than 5% of all cases. Much of the remaining variations could be due to the co-inheritance of multiple low penetrant variants. The identification of all the susceptibility alleles could have public health relevance in the near future. To test the hypothesis that what are considered polymorphisms in human CRC genes could constitute low-risk alleles, we selected eight common SNPs for a pilot association study in 1785 cases and 1722 controls. One SNP, rs3219489:G>C (MUTYH Q324H) seemed to confer an increased risk of rectal cancer in homozygous status (OR=1.52; CI=1.06-2.17). When the analysis was restricted to our 'super-controls', healthy individuals with no family history for cancer, also rs1799977:A>G (MLH1 I219V) was associated with an increased risk in both colon and rectum patients with an odds ratio of 1.28 (CI=1.02-1.60) and 1.34 (CI=1.05-1.72), respectively (under the dominant model); while 2 SNPs, rs1800932:A>G (MSH6 P92P) and rs459552:T>A (APC D1822V) seemed to confer a protective effect. The latter, in particular showed an odds ratio of 0.76 (CI=0.60-0.97) among colon patients and 0.73 (CI=0.56-0.95) among rectal patients. In conclusion, our study suggests that common variants in human CRC genes could constitute low-risk alleles.
Preoperative irradiation with 5 × 5 Gy in randomized trials reduces local recurrence rate and may improve survival in patients with resectable rectal cancer.
The aim of this study was to determine whether the same favorable effects could be observed in a population-based study.
This study was conducted via a retrospective analysis of prospectively collected data from the Swedish Rectal Cancer Registry.
This study examined population-based data from Sweden.
All newly diagnosed rectal cancers in Sweden are reported to the Swedish Rectal Cancer Registry.
Between 1995 and 2001, 6878 patients (stages I-III) were operated on with an anterior resection, an abdominoperineal resection, or a Hartmann's procedure. Short-course irradiation was given to 41% of patients preoperatively. To reduce bias, patients operated on with a Hartmann procedure or older than 75 years were excluded when 5-year survival was analyzed (n = 3466). Tumors were analyzed according to height (0-5 cm, 6-10 cm, 11-15 cm).
Five-year cumulative local recurrence and survival rates.
The 5-year cumulative local recurrence rate was 6.3% (95% CI 5.4-7.4) for patients receiving preoperative irradiation and 12.1% (95% CI 10.8-13.5) for patients not receiving preoperative irradiation. Multivariate analyses indicated the risk of local recurrence was 50% lower for patients receiving preoperative irradiation compared with patients not receiving irradiation (hazard ratio = 0.50; 95% CI 0.40-0.62). Among patients younger than 76 years and operated on with an anterior resection or abdominoperineal resection, the 5-year cumulative survival rate was 0.70 (95% CI 0.69-0.72). Disease-free and overall survivals were higher in irradiated patients, and the difference was statistically significant in low tumors.
In this population-based analysis, the favorable effect of preoperative short-course irradiation on local recurrence rates, seen in randomized trials, was confirmed for the entire Swedish population irrespective of tumor height and stage. Data also suggested an effect on 5-year survival, especially in patients with low tumors (0-5 cm).
PURPOSE: To analyze the occurrence of second cancers in patients with rectal cancer treated with external radiotherapy (RT) in addition to surgery. PATIENTS AND METHODS: The analyses were based on the Uppsala Trial (completed in 1985), with patients randomly assigned to preoperative RT to all stages or postoperative RT for stage II and III cancers, and the Swedish Rectal Cancer Trial (completed in 1990), with patients randomly assigned to preoperative RT or surgery alone. Patients from the trials were matched against the Swedish Cancer Registry. RESULTS: A total of 115 (7%) of the 1,599 patients developed 122 second cancers. More patients treated with RT developed a second cancer (relative risk [RR], 1.85; 95% CI, 1.23 to 2.78). A significant increased risk for second cancers in the RT group was seen in organs within or adjacent to the irradiated volume (RR, 2.04; 95% CI, 1.10 to 3.79) but not outside the irradiated volume (RR, 1.78; 95% CI, 0.97 to 3.27). For the Swedish Rectal Cancer Trial, 20.3% of the RT patients got either a local recurrence or a second cancer, compared with 30.7% of the non-RT patients (RR, 0.55; 95% CI, 0.44 to 0.70). CONCLUSION: An increased risk of second cancers was found in patients treated with RT in addition to surgery for a rectal cancer, which was mainly explained by an increase in the risk of second cancers in organs within or adjacent to the irradiated volume. However, a favorable effect of radiation seemed to dominate, as shown by the reduced risk of the sum of local recurrences and second cancers.