Increased cumulative incidence of prostate malignancies in colorectal cancer patients

Secondary Cancers After Radiation Therapy for Primary Prostate or Rectal Cancer

Literature about the risk of secondary cancer after radiation therapy (RT) of prostate and rectal cancer reveals contradictory results. We conducted a meta-analysis to examine whether the RT induces secondary rectal or prostate cancer in patients, respectively, with prostate or rectal cancer. All studies published in Medline or Pubmed up to March 3, 2015, containing RT of primary rectal or prostate cancer, and providing risk estimates of secondary prostate or rectal cancer were considered as eligible. Relative risk (RR) and standardized incidence ratios (SIR) were calculated using the random-effects model. Twenty studies met the inclusion criteria. 12 of them were from the Surveillance, Epidemiology, and End Results (SEER) database. For prostate cancer patients, pooled adjusted RRs or SIRs did not show an effect on the risk of secondary rectal cancer. However, notwithstanding the limitations of SEER-based studies, the subgroup of prostate cancer patients receiving external beam radiation therapy (EBRT) showed an increased risk of rectal cancer. For rectal cancer patients, pooled adjusted RR of prostate cancer was 1.12 (95 % CI, 0.44-2.8) and SIR was 0.40 (95 % CI, 0.29-0.55). All studies included in the SIR analysis of rectal cancer were derived from the SEER data source. Based on current evidence, RT for prostate cancer patients had no effect on rectal cancer incidence, except for patients who received EBRT therapy. However, compared with the general population, RT for rectal cancer is associated with a decreased prostate cancer risk as found in SEER-based studies.

Prostate cancer patients may have an increased risk of coexisting advanced colorectal neoplasms

Background/aims

Patients being treated for prostate cancer (PCa) have an increased risk of developing colorectal cancer. However, whether PCa patients are inherently at a higher risk of colorectal neoplasms (CRNs) is unknown. We aimed to investigate the risk of CRNs in PCa patients.

Materials and methods

Patients who had been diagnosed with PCa at a tertiary medical center and had colonoscopy within 1 year of the PCa diagnosis were investigated. Patients were propensity-matched 1:2 by age and body mass index to asymptomatic control subjects who had undergone colonoscopy for routine health screening. CRN was defined as histological confirmation of an adenoma or adenocarcinoma component. Advanced CRN was defined as any of the following: 1) histological findings of high-grade dysplasia, 2) inclusion of villous features, 3) tumor ≥1 cm in size, or 4) presence of an adenocarcinoma. Risk factors for CRN and advanced CRN were evaluated by univariate and multivariate analysis.

Results

A total of 191 patients diagnosed with PCa had colonoscopies within 1 year of PCa diagnosis. Of these, 23 patients with a history of previous malignancy and seven with incomplete colonoscopies were excluded, leaving 161 patients in the PCa group. Although presence of PCa was not a significant risk factor for CRN by multivariate analysis, PCa was a significant risk factor for advanced CRN (odds ratio [OR] 3.300; 95% confidence interval [CI] 1.766–6.167; P<0.001). Other significant risk factors for advanced CRN were age (OR 1.050; 95% CI 1.003–1.009; P=0.036) and body mass index (OR 1.205; 95% CI 1.067–1.361; P=0.003), whereas aspirin use (OR 0.414; 95% CI 0.173–0.990; P=0.047) was a preventive factor.

Conclusion

The risk of advanced CRN may be significantly increased in patients with PCa. Patients with PCa should have a colonoscopy at the time of PCa diagnosis.

Genome-wide linkage analyses of hereditary prostate cancer families with colon cancer provide further evidence for a susceptibility locus on 15q11-q14

The search for susceptibility loci in hereditary prostate cancer (HPC) is challenging because of locus and disease heterogeneity. One approach to reduce disease heterogeneity is to stratify families on the basis of the occurrence of multiple cancer types. This method may increase the power for detecting susceptibility loci, including those with pleiotropic effects. We have completed a genome-wide SNP linkage analysis of 96 HPC families, each of which has one or more first-degree relatives with colon cancer (CCa), and further analyzed the subset of families with two or more CCa cases (n = 27). When only a prostate cancer (PCa) phenotype was considered to be affected, we observed suggestive evidence for linkage (LOD ≥1.86) at 15q14, 18q21 and 19q13 in all families, and at 1p32 and 15q11-q14 in families with two or more CCa cases. When both the PCa and CCa phenotypes were considered affected, suggestive evidence for linkage was observed at 11q25, 15q14 and 18q21 in all families, and at 1q31, 11q14 and 15q11-14 in families with two or more CCa cases. The strongest linkage signal was identified at 15q14 when both PCa and CCa phenotypes were considered to be affected in families with two or more CCa cases (recessive HLOD = 3.88). These results provide further support for the presence of HPC susceptibility loci on chromosomes 11q14, 15q11-q14 and 19q13 and highlight loci at 1q31, 11q, 15q11-14 and 18q21 as having possible pleiotropic effects. This study shows the benefit of using a comprehensive family cancer history to create more genetically homogenous subsets of HPC families for linkage analyses.

Do patients undergo prostate examination while having a colonoscopy?

OBJECTIVES

To determine the rate at which physicians report performing a digital rectal examination and comment on the prostate gland before performing colonoscopy in men 50 to 70 years of age.

METHODS

A retrospective chart review of all men 50 to 70 years of age who had a colonoscopy in Kingston, Ontario, in 2005 was completed. It was noted whether each physician described performing a digital rectal examination before the colonoscopy, and if so, whether he or she commented on the prostate.

RESULTS

In 2005, 846 eligible colonoscopies were performed by 17 physicians in Kingston, Ontario. In 29.2% of cases, the physician made no comment about having performed a digital rectal examination; in 55.8% of cases, the physician commented on having completed a digital rectal examination but said nothing about the prostate; and in 15.0% of cases, the physician made a comment regarding the prostate. No physician consistently commented on the prostate for all patients, and in no circumstances was direct referral to another physician or follow-up suggested.

DISCUSSION

A colonoscopy presents an ideal opportunity for physicians to use a digital rectal examination to assess for prostate cancer. Physicians performing colonoscopies in men 50 to 70 years of age should pay special attention to the prostate while performing a digital rectal examination before colonoscopy. This novel concept may help maximize resources for cancer screening and could potentially increase the detection rate of clinically palpable prostate cancer.

Temporal relationship between prostate brachytherapy and the diagnosis of colorectal cancer

PURPOSE

To identify the location of pretreatment and posttreatment colorectal malignancies and posttreatment colorectal polyps in patients with clinically localized prostate cancer managed with brachytherapy.

METHODS AND MATERIALS

From April 1995 through July 2004, 1,351 consecutive patients underwent brachytherapy for clinical stage T1b-T3a (American Joint Committee on Cancer, 2002) prostate cancer. Supplemental external beam radiotherapy (XRT) was administered to 699 patients. The median follow-up was 4.6 years. Operative and pathology reports were reviewed for all patients with pretreatment and posttreatment colorectal cancer and posttreatment colorectal polyps. Multiple parameters were evaluated for the development of colorectal cancer or colorectal polyps.

RESULTS

Colorectal cancer was diagnosed in 23 and 25 patients before and after prostate brachytherapy, respectively. No differences were identified in the distribution of colorectal cancers either before or after treatment (3 and 4 rectal cancers in the pre- and postbrachytherapy cohorts). Thirty-five of the 48 colorectal cancers (73%) were diagnosed within 5 years of brachytherapy with a peak incidence 1 year after brachytherapy. One hundred ninety-two colorectal polyps were diagnosed after brachytherapy, 160 (83%) occurred within 4 years of brachytherapy, and only 27 (14%) were located in the rectum. In multivariate Cox regression analysis, prostate D(90) (minimum percentage of the dose covering 90% of the target volume) predicted for posttreatment colorectal cancer. Rectal polyps were most closely related to patient age and percent positive biopsies, whereas sigmoid/colon polyps were best predicted by patient age, planning volume, and supplemental XRT.

CONCLUSIONS

Colorectal cancer was diagnosed with equal frequency before and after brachytherapy with comparable geographic distributions. In addition, the vast majority of postbrachytherapy colorectal polyps were located beyond the confines of the rectum.