Utility of ctDNA in predicting response to neoadjuvant chemoradiotherapy and prognosis assessment in locally advanced rectal cancer: A prospective cohort study

BACKGROUND

For locally advanced rectal cancer (LARC) patients who receive neoadjuvant chemoradiotherapy (nCRT), there are no reliable indicators to accurately predict pathological complete response (pCR) before surgery. For patients with clinical complete response (cCR), a "Watch and Wait" (W&W) approach can be adopted to improve quality of life. However, W&W approach may increase the recurrence risk in patients who are judged to be cCR but have minimal residual disease (MRD). Magnetic resonance imaging (MRI) is a major tool to evaluate response to nCRT; however, its ability to predict pCR needs to be improved. In this prospective cohort study, we explored the value of circulating tumor DNA (ctDNA) in combination with MRI in the prediction of pCR before surgery and investigated the utility of ctDNA in risk stratification and prognostic prediction for patients undergoing nCRT and total mesorectal excision (TME).

METHODS AND FINDINGS

We recruited 119 Chinese LARC patients (cT3-4/N0-2/M0; median age of 57; 85 males) who were treated with nCRT plus TME at Fudan University Shanghai Cancer Center (China) from February 7, 2016 to October 31, 2017. Plasma samples at baseline, during nCRT, and after surgery were collected. A total of 531 plasma samples were collected and subjected to deep targeted panel sequencing of 422 cancer-related genes. The association among ctDNA status, treatment response, and prognosis was analyzed. The performance of ctDNA alone, MRI alone, and combining ctDNA with MRI was evaluated for their ability to predict pCR/non-pCR. Ranging from complete tumor regression (pathological tumor regression grade 0; pTRG0) to poor regression (pTRG3), the ctDNA clearance rate during nCRT showed a significant decreasing trend (95.7%, 77.8%, 71.1%, and 66.7% in pTRG 0, 1, 2, and 3 groups, respectively, P = 0.008), while the detection rate of acquired mutations in ctDNA showed an increasing trend (3.8%, 8.3%, 19.2%, and 23.1% in pTRG 0, 1, 2, and 3 groups, respectively, P = 0.02). Univariable logistic regression showed that ctDNA clearance was associated with a low probability of non-pCR (odds ratio = 0.11, 95% confidence interval [95% CI] = 0.01 to 0.6, P = 0.04). A risk score predictive model, which incorporated both ctDNA (i.e., features of baseline ctDNA, ctDNA clearance, and acquired mutation status) and MRI tumor regression grade (mrTRG), was developed and demonstrated improved performance in predicting pCR/non-pCR (area under the curve [AUC] = 0.886, 95% CI = 0.810 to 0.962) compared with models derived from only ctDNA (AUC = 0.818, 95% CI = 0.725 to 0.912) or only mrTRG (AUC = 0.729, 95% CI = 0.641 to 0.816). The detection of potential colorectal cancer (CRC) driver genes in ctDNA after nCRT indicated a significantly worse recurrence-free survival (RFS) (hazard ratio [HR] = 9.29, 95% CI = 3.74 to 23.10, P < 0.001). Patients with detectable driver mutations and positive high-risk feature (HR_feature) after surgery had the highest recurrence risk (HR = 90.29, 95% CI = 17.01 to 479.26, P < 0.001). Limitations include relatively small sample size, lack of independent external validation, no serial ctDNA testing after surgery, and a relatively short follow-up period.

CONCLUSIONS

The model combining ctDNA and MRI improved the predictive performance compared with the models derived from individual information, and combining ctDNA with HR_feature can stratify patients with a high risk of recurrence. Therefore, ctDNA can supplement MRI to better predict nCRT response, and it could potentially help patient selection for nonoperative management and guide the treatment strategy for those with different recurrence risks.

Epidemiology and Mechanisms of the Increasing Incidence of Colon and Rectal Cancers in Young Adults

In contrast to the decreasing incidence of colorectal cancer (CRC) in older populations, the incidence has nearly doubled in younger adults since the early 1990s. Approximately 1 in 10 new diagnoses of CRC are now made in individuals 50 years or younger. Patients' risk of CRC has been calculated largely by age and family history, yet 3 of 4 patients with early-onset CRC have no family history of the disease. Rapidly increasing incidence rates in younger people could result from generational differences in diet, environmental exposures, and lifestyle factors. We review epidemiologic trends in CRC, data on genetic and nongenetic risk factors, and new approaches for determining CRC risk. These may identify individuals likely to benefit from early screening and specialized surveillance.

Selection Criteria in Colorectal Cancer Screening

The authors report the results of a risk questionnaire (RQ) used in a population-based screening program for colorectal cancer. The positive predictive value (PPV) for cancer or adenoma was evaluated for the Hemoccult test (HO) and for all RQ items (symptoms, personal and familial risk) in 8,114 cases, by univariate and multivariate analysis. A significant correlation with the presence of cancer or adenoma was observed for HO-positive tests, whereas a significant correlation was absent for most RQ variables. The use of an RQ in screening practice is disregarded since it does not improve the rate of cancer detection. Moreover, the increase in the detection rate of HO-negative adenomas does not justify the high rate (0.18) of screening responders selected for endoscopic diagnostic workup, a figure which influences negatively the overall compliance to screening.

Colorectal Chemoprevention

With over 1 million cases diagnosed worldwide each year - incidence which seems to rise with the progressive westernization of lifestyles in Asian and African populations - colorectal cancer is the third most commonly diagnosed cancer in both men and women. Colorectal neoplasms and/or pre-neoplasms can be prevented by interfering with the various steps of oncogenesis, which begins with uncontrolled epithelial cell replication, continues with the formation of adenomas and eventually evolves into malignancy. The knowledge described herein will help to reduce and prevent this malignancy, which is one of the most frequent neoplasms in some developed countries. Genetics, experimental and epidemiologic studies suggest that colorectal cancer results from complex interactions between inherited susceptibility and environmental factors. Primary prevention involves the identification of genetic, biologic, and environmental factors that are etiologic or pathogenic in the development of cancer, and subsequent complete or significant interference with their effects on carcinogenesis.

Adequate Margins to Prevent Local Re-recurrence of Rectal Cancer: Viewpoint of Pathological Findings

BACKGROUND

A sufficient surgical margin is critical for preventing re-recurrence and achieving R0 status after resection of a local recurrence of rectal cancer (LRRC).

PATIENTS AND METHODS

Re-recurrence-free survival was analyzed in 110 cases of LRRC according to histological type of primary lesion. The circumferential resection margin (CRM) was classified as 'R1' (x=0 μm), 'R0 shortness' (0 μm <x<2,000 μm), or 'R0 longness' (x≥2,000 μm). The histological change from the primary lesion to the recurrent lesion was classified as 'No change pattern', from well- to moderately-differentiated (W/M) to an expanding lesion; as 'Change pattern', from W/M to an infiltrating lesion.

RESULTS

Re-recurrence-free survival was better in 'R0 longness' than 'R0 shortness' groups and showed that 'No change pattern' cases had considerably better prognosis than 'Change pattern' cases.

CONCLUSION

Ensuring a CRM >2,000 μm during resection of LRRC is more likely to prevent re-recurrence. Cases with poorly differentiated carcinoma from the primary lesion to the recurrent lesion tend to have poor prognoses.

Is there a place for organ preservation in infiltrating rectal cancer?

Neoadjuvant chemoradiotherapy followed by total mesorectal excision is currently the standard of care for locally advanced rectal cancers. However, this therapeutic approach does not take into account response to neoadjuvant treatment, which can go up to a pathologic complete response in 10-20% of the patients. Moreover, despite its efficacy in terms of local control and survival, radical surgery is associated with a significant risk of postoperative morbidity, anastomotic leakage, permanent stoma, impaired quality of life, bowel and genitourinary dysfunction. Based on these adverse events, new strategies of organ preservation have emerged recently. They include, in case of suspicion of complete tumor response, both "watch and wait" strategy and local excision of the residual scar. They seem attractive options, both for patients and surgeons, in terms of postoperative results. But few high-quality studies are available and fears remain regarding oncologic results and reproducibility of published results. Before these strategies can be recommended, large prospective randomized studies are still needed. The aim of this review is to discuss these two options for organ preservation, based on the current literature, with a special focus on oncologic outcomes.

Preventive cancer care for the elderly

There is a great need for effective cancer prevention programs for the elderly. Unfortunately, the elderly have been omitted from most studies of cancer prevention; little is currently known concerning the benefits, risks, and feasibility of most primary and secondary cancer prevention measures in this segment of the population. Available data justify annual casefinding activities in the office of the primary care physician for breast cancer in elderly women and colorectal cancer in elderly persons of both sexes. PAP smear screening is also indicated for elderly women who have had few or no PAP smear in the past. There is some evidence that the health beliefs and practices of elderly persons and their physicians may impede the utilization of available cancer prevention measures. Further research is needed to define the efficacy of cancer prevention measures for the elderly and to improve the delivery of these measures to the elderly population.

Systematic review and meta-analysis of rectal washout on risk of local recurrence for cancer

BACKGROUND

It has been shown that intraluminal washout (WO) can prevent local recurrence (LR) of rectal cancer. This meta-analysis was to evaluate the association of rectal WO and the risk of LR after anterior resection in patients with rectal cancer.

METHODS

The relevant studies were identified by a search of the MEDLINE, Embase, Wiley Online Library, and Cochrane Oral Health Group Specialized Register with no restrictions on October 18, 2013, and these studies were included in a systematic review and meta-analysis. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in fixed effects model.

RESULTS

A total of nine studies were included in our study, yielding a total of 5519 patients, and pooled ORs for overall LR in corresponding subgroups were calculated. Rectal WO was associated with a lower risk for LR (240/4176, 5.75% versus 9.75%, 131/1343, OR = 0.53, 95% CI = 0.42-0.68, and P < 0.00001) in patients with anterior resection, having total mesorectal excisions (234/3942, 5.93% versus 9.34%, 97/1039, OR = 0.59, 95% CI = 0.46-0.75, and P < 0.00001), and after radical resection (RR; 122/2665, 4.99% versus 8.90%, 74/831, OR = 0.56, 95% CI = 0.41-0.78, and P = 0.0005), with an overall LR rate of 6.72% (371/5519). But, the stability of RRs is not high in the total mesorectal excisions or RR subgroup by sensitivity analysis.

CONCLUSIONS

The use of rectal WO decreases risks of LR in patients after anterior resection of cancer.

[The distal resection margin in rectal cancer surgery]

Spread of the tumor in the distal direction is an important factor that must be considered when performing organ-serving surgery for rectal cancer. Particular relevance it has acquired in recent years due to the general tendency to expand the indications for the preservation of natural reflex-apparatus in patients with medium- and lower-ampullar part of the rectum.

Red meat intake may increase the risk of colon cancer in Japanese, a population with relatively low red meat consumption

Asian populations have changed from traditional to Westernized diets, with increased red meat intake. They are suggested to be particularly susceptible to the adverse effects of red meat on the development of colorectal cancers, however, few prospective studies of this putative link have been conducted. We examined associations between the consumption of red and processed meat and the risk of subsite-specific colorectal cancer by gender in a large Japanese cohort. During 1995-1998, a validated food frequency questionnaire was administered to 80,658 men and women aged 45-74 years. During 758,116 person-years of follow-up until the end of 2006, 1,145 cases of colorectal cancer were identified. Higher consumption of red meat was significantly associated with a higher risk of colon cancer among women [multivariate hazard ratios (95%CIs) for the highest versus lowest quintiles (HR): 1.48 (1.01, 2.17; trend p=0.03)], as was higher consumption of total meat among men [HR=1.44 (1.06, 1.98; trend p=0.07)]. By site, these positive associations were found for the risk of proximal colon cancer among women and for distal colon cancer among men. No association was found between the consumption of processed meat and risk of either colon or rectal cancer. In conclusion, red meat intake may modestly increase the risk of colon cancer in middle-aged Japanese, although the highest quintile of red meat consumption could be considered moderate by Western standards.

A decision aid to support informed choices about bowel cancer screening among adults with low education: randomised controlled trial

OBJECTIVE

To determine whether a decision aid designed for adults with low education and literacy can support informed choice and involvement in decisions about screening for bowel cancer.

DESIGN

Randomised controlled trial.

SETTING

Areas in New South Wales, Australia identified as socioeconomically disadvantaged (low education attainment, high unemployment, and unskilled occupations).

PARTICIPANTS

572 adults aged between 55 and 64 with low educational attainment, eligible for bowel cancer screening.

INTERVENTION

Patient decision aid comprising a paper based interactive booklet (with and without a question prompt list) and a DVD, presenting quantitative risk information on the possible outcomes of screening using faecal occult blood testing compared with no testing. The control group received standard information developed for the Australian national bowel screening programme. All materials and a faecal occult blood test kit were posted directly to people's homes.

MAIN OUTCOME MEASURES

Informed choice (adequate knowledge and consistency between attitudes and screening behaviour) and preferences for involvement in screening decisions.

RESULTS

Participants who received the decision aid showed higher levels of knowledge than the controls; the mean score (maximum score 12) for the decision aid group was 6.50 (95% confidence interval 6.15 to 6.84) and for the control group was 4.10 (3.85 to 4.36; P<0.001). Attitudes towards screening were less positive in the decision aid group, with 51% of the participants expressing favourable attitudes compared with 65% of participants in the control group (14% difference, 95% confidence interval 5% to 23%; P=0.002). The participation rate for screening was reduced in the decision aid group: completion of faecal occult blood testing was 59% v 75% in the control group (16% difference, 8% to 24%; P=0.001). The decision aid increased the proportion of participants who made an informed choice, from 12% in the control group to 34% in the decision aid group (22% difference, 15% to 29%; P<0.001). More participants in the decision aid group had no decisional conflict about the screening decision compared with the controls (51% v 38%; P=0.02). The groups did not differ for general anxiety or worry about bowel cancer.

CONCLUSIONS

Tailored decision support information can be effective in supporting informed choices and greater involvement in decisions about faecal occult blood testing among adults with low levels of education, without increasing anxiety or worry about developing bowel cancer. Using a decision aid to make an informed choice may, however, lead to lower uptake of screening. Trial registration ClinicalTrials.gov NCT00765869 and Australian New Zealand Clinical Trials Registry 12608000011381.

Digital rectal examination for prostate and rectal tumour: knowledge and experience of final year medical students

BACKGROUND

It is most pertinent that medical students are taught the necessary skills for digital rectal examination (DRE) before they become doctors.

OBJECTIVE

The study is to assess the knowledge and experience of final year medical students regarding DRE for prostate and rectal tumours.

METHODS

Well-structured questionnaire were administered to each of the final year medical students of Ladoke Akintola University of Technology a week to their final examinations.

RESULTS

Response was received from 127 (60%) of the students, 124 (97.6%) agreed that they have been taught DRE. Most of the students, 102 (80.3%), have done one to five DRE, three (2.4%) and have never performed DRE while none of the students have done more than ten DRE. Only in 49 (38.6%) of cases were the findings of the students on DRE always confirmed by a doctor. Nine students (7.1%) have never felt a clinical BPH and none had felt it more than five times. Sixty-six (52.0%) have never felt a malignant prostate and none of the students have felt it up to three times. Most of the students, 106 (83.5%), have never felt a rectal tumour on DRE Only five (3.9%) felt very confident of their ability to give an opinion based on their findings on DRE while 105 (82.7%) felt reasonably confident

CONCLUSIONS

The students have been taught DRE and a good number of them have performed it. Few of the DRE done by the students were cross-checked by a doctor. Most of the students have problems differentiating BPH from cancer of the prostate and many of them were not very confident of their findings on DRE.

Screening for cancer in adults

With careful selection of procedures, frequencies and risk groups, the periodic screening of adults for cancer can be a highly cost-effective medical activity. This paper summarizes the evidence of effectiveness of screening, the expected reduction in mortality, the risks and costs of screening, and the cost-effectiveness of screening strategies for cancer of the breast, colon, lung, cervix, endometrium and oral cavity. Some of the most pressing questions to be discussed concern the value of mammography, the frequency of the Pap smear, sigmoidoscopy, the value of chest X-rays and sputum cytology in the detection of lung cancer, and the current status of screening for cancers of the endometrium and oral cavity.

The relationship between family physician density and health related outcomes: the Canadian evidence

This paper analyzes if and to what extent the density of family physicians influences health related outcomes in Canada. The density of family physicians in a given region is assumed to serve as proxy for the access to and availability of desirable primary care services. We use self-reported general and mental health status as our overall health outcome measures. We also use several quality of care indicators reflecting whether or not an individual received influenza immunization, mammography, pap smear, and colorectal cancer screening if at high-risk. The empirical results of this study suggest that an additional family physician per 10,000 population has a statistically significant impact in the order of 2% to 4% on self-reported general health status, as well as, other quality of care outcomes. We also find important socioeconomic and demographic factors, such as income, education and immigrant status, influencing health related outcomes considered in this study. Understanding the influence of physician density and socioeconomic factors on health related outcomes are important considerations for health policy and planning.

Long-term oncologic results of patients with distal rectal cancer treated by local excision with or without adjuvant treatment

AIM

The aim of this study is to review long-term oncologic results of local excision (LE) and to investigate the validity and feasibility of LE as a treatment option for distal rectal cancer.

MATERIALS AND METHODS

Seventy-six patients who underwent LE for distal rectal adenocarcinoma with curative intent from 1991 to 2000 at Severance Hospital Yonsei University Medical Center, Seoul, Korea were enrolled in this study.

RESULTS

Preoperative transrectal ultrasonography revealed 3 cases of uT0, 55 cases of uT1 and 18 cases of uT2. Postoperative pathologic examination revealed 10 cases of pT0 (where no residual cancer cells remained), 11 cases of pTis, 37 cases of pT1, 16 cases of pT2, and 2 cases of pT3. Eleven out of 37 patients with pT1 tumors received adjuvant radiation therapy. Among 16 patients with pT2 tumor, 7 undertook salvage operation and 8 received adjuvant therapy. The median follow-up period was 84.9 months. Local recurrence was observed in six patients. The 5-year local recurrence-free survival rate (LFS) was 89.4% in the pT1 group and 75.0% in the pT2 group (p = 0.012). Among the patients with pT1 cancer, those who received adjuvant radiation therapy demonstrated a 5-year LFS of 100%, compared to those who did not, 76.0% (p = 0.038).

CONCLUSION

Our results imply a potential role of LE and adjuvant radiation as an option for the treatment of distal rectal cancer, and that even for pT1 carcinoma, LE alone might not be a valid modality.

Diet and vitamin or mineral supplementation and risk of rectal cancer in Canada

The study examines the relation of diet and vitamin or mineral supplementation with risk of rectal cancer. Mailed questionnaires were completed by 1 380 newly diagnosed patients with histologically confirmed rectal cancer and 3 097 population controls between 1994 and 1997 in seven Canadian provinces. Measurement included information on socio-economic status, lifestyle, diet and vitamin or mineral supplementation. We derived odds ratios and 95% confidence intervals through unconditional logistic regression. Total of consumption of vegetables, fruit and whole-grain products did not reduce the risk of rectal cancer. Consumption of cruciferous vegetables was inversely associated with risk of rectal cancer among women only, as did chicken intake among men. The strongest dietary association with increased rectal cancer risk appeared in males with increasing total fat intake and in females with bacon intake. Vitamin and mineral supplementation showed significant inverse associations with rectal cancer in women only. These findings suggest that dietary risk factors for rectal cancer in women may differ from those in men.