Chemoradiation versus surgery for superficial esophageal squamous cell carcinoma after noncurative endoscopic submucosal dissection: comparison of long-term oncologic outcomes.

BACKGROUND: Esophagectomy is the standard adjuvant treatment for superficial esophageal squamous cell carcinoma (SESCC) following noncurative endoscopic submucosal dissection (ESD). However, recent reports have also shown that ESD with adjuvant chemoradiotherapy (CRT) has promising results. This retrospective study aimed to elucidate the efficacy of CRT compared to surgery in patients with SESCC after noncurative ESD. METHODS: This study retrospectively compared the long-term outcomes of patients who received adjuvant treatment with surgery or CRT after noncurative ESD for SESCC. RESULTS: Data were collected from 60 patients who developed SESCC after noncurative ESD, 34 of whom received adjuvant chemoradiotherapy (CRT) and 26 underwent esophagectomy. The median follow-up periods were 46 and 56 months in the CRT and esophagectomy groups, respectively. The median patient age was significantly higher in the CRT group than in the esophagectomy group (69 vs. 65 years, p = 0.0054). CRT was completed in all patients, and the incidence of grade ≥ 3 nonhematologic adverse events was 6%. The overall and disease-free survival did not significantly differ between the two groups. CONCLUSIONS: CRT following ESD seems a promising nonsurgical strategy for optimizing the selection of therapies for high-risk SESCC and warrant further investigation.

Disparities in radiation therapy utilization for cancer patients in Victoria.

INTRODUCTION: To evaluate the proportion of cancer patients who received radiation therapy (RT) within 12 months of cancer diagnosis (RTU12) and identify factors associated with RTU12. METHODS: This is a population-based cohort of individuals with incident cancer, diagnosed between 2013 and 2017 in Victoria. Data linkages were performed between the Victorian Cancer Registry and Victorian Radiotherapy Minimum Dataset. The primary outcome was the proportion of patients who had RTU12. For the three most common cancers (i.e., prostate, breast and lung cancer), the time trend in RTU12 and factors associated with RTU12 were evaluated. RESULTS: The overall RTU12 in our study cohort was 26-20% radical RT and 6% palliative RT. Of the 21,735 men with prostate cancer, RTU12 was 17%, with no significant change over time (P-trend = 0.53). In multivariate analyses, increasing age and lower socioeconomic status were independently associated with higher RTU12 for prostate cancer. Of the 20,883 women with breast cancer, RTU12 was 64%, which increased from 62% in 2013 to 65% in 2017 (P-trend < 0.05). In multivariate analyses, age, socioeconomic status and area of residency were independently associated with RTU12 for breast cancer. Of the 13,093 patients with lung cancer, RTU12 was 42%, with no significant change over time (P-trend = 0.16). In multivariate analyses, younger age, male and lower socioeconomic status were independently associated with higher RTU12. CONCLUSION: In this large population-based state-wide cohort of cancer patients, only 1 in 4 had RT within 12 months of diagnosis. There were marked sociodemographic disparities in RTU12 for prostate, breast and lung cancer patients.

Machine learning predicts cancer subtypes and progression from blood immune signatures.

Clinical adoption of immune checkpoint inhibitors in cancer management has highlighted the interconnection between carcinogenesis and the immune system. Immune cells are integral to the tumour microenvironment and can influence the outcome of therapies. Better understanding of an individual's immune landscape may play an important role in treatment personalisation. Peripheral blood is a readily accessible source of information to study an individual's immune landscape compared to more complex and invasive tumour bioipsies, and may hold immense diagnostic and prognostic potential. Identifying the critical components of these immune signatures in peripheral blood presents an attractive alternative to tumour biopsy-based immune phenotyping strategies. We used two syngeneic solid tumour models, a 4T1 breast cancer model and a CT26 colorectal cancer model, in a longitudinal study of the peripheral blood immune landscape. Our strategy combined two highly accessible approaches, blood leukocyte immune phenotyping and plasma soluble immune factor characterisation, to identify distinguishing immune signatures of the CT26 and 4T1 tumour models using machine learning. Myeloid cells, specifically neutrophils and PD-L1-expressing myeloid cells, were found to correlate with tumour size in both the models. Elevated levels of G-CSF, IL-6 and CXCL13, and B cell counts were associated with 4T1 growth, whereas CCL17, CXCL10, total myeloid cells, CCL2, IL-10, CXCL1, and Ly6Cintermediate monocytes were associated with CT26 tumour development. Peripheral blood appears to be an accessible means to interrogate tumour-dependent changes to the host immune landscape, and to identify blood immune phenotypes for future treatment stratification.

Temporal determinants of tumour response to neoadjuvant rectal radiotherapy.

INTRODUCTION: In locally advanced rectal cancer, longer delay to surgery after neoadjuvant radiotherapy increases the likelihood of histopathological tumour response. Chronomodulated radiotherapy in rectal cancer has recently been reported as a factor increasing tumour response to neoadjuvant treatment in patients having earlier surgery, with patients receiving a larger proportion of afternoon treatments showing improved response. This paper aims to replicate this work by exploring the impact of these two temporal factors, independently and in combination, on histopathological tumour response in rectal cancer patients. METHODS: A retrospective review of all patients with rectal adenocarcinoma who received long course (≥24 fractions) neoadjuvant radiotherapy with or without chemotherapy at a tertiary referral centre was conducted. Delay to surgery and radiotherapy treatment time were correlated to clinicopathologic characteristics with a particular focus on tumour regression grade. A review of the literature and meta-analysis were also conducted to ascertain the impact of time to surgery from preoperative radiotherapy on tumour regression. RESULTS: From a cohort of 367 patients, 197 patients met the inclusion criteria. Complete pathologic response (AJCC regression grade 0) was seen in 46 (23%) patients with a further 44 patients (22%) having at most small groups of residual cells (AJCC regression grade 1). Median time to surgery was 63 days, and no statistically significant difference was seen in tumour regression between patients having early or late surgery. There was a non-significant trend towards a larger proportion of morning treatments in patients with grade 0 or 1 regression (p = 0.077). There was no difference in tumour regression when composite groups of the two temporal variables were analysed. Visualisation of data from 39 reviewed papers (describing 27379 patients) demonstrated a plateau of response to neoadjuvant radiotherapy after approximately 60 days, and a meta-analysis found improved complete pathologic response in patients having later surgery. CONCLUSIONS: There was no observed benefit of chronomodulated radiotherapy in our cohort of rectal cancer patients. Review of the literature and meta-analysis confirms the benefit of delayed surgery, with a plateau in complete response rates at approximately 60-days between completion of radiotherapy and surgery. In our cohort, time to surgery for the majority of our patients lay along this plateau and this may be a more dominant factor in determining response to neoadjuvant therapy, obscuring any effects of chronomodulation on tumour response. We would recommend surgery be performed between 8 and 11 weeks after completion of neoadjuvant radiotherapy in patients with locally advanced rectal cancer.

Custom-designed Small Animal focal iRradiation Jig (SARJ): design, manufacture and dosimetric evaluation.

OBJECTIVE: Preclinical animal models allow testing and refinement of novel therapeutic strategies. The most common preclinical animal irradiators are fixed source cabinet irradiators, which are vastly inferior to clinical linear accelerators capable of delivering highly conformal and precise treatments. The purpose of this study was to design, manufacture and test an irradiation jig (small animal focal irradiation jig, SARJ) that would enable focal irradiation of subcutaneous tumours in a standard fixed source cabinet irradiator. METHODS AND MATERIALS: A lead shielded SARJ was designed to rotate animal holders about the longitudinal axis and slide vertically from the base plate. Radiation dosimetry was undertaken using the built-in ion chamber and GAFChromic RTQA2 and EBT-XD films. Treatment effectiveness was determined by irradiating mice with subcutaneous melanoma lesions using a dose of 36 Gy in three fractions (12 Gy x 3) over three consecutive days. RESULTS: The SARJ was tested for X-ray shielding effectiveness, verification of dose rate, total dose delivered to tumour and dose uniformity. Accurate and uniform delivery of X-ray dose was achieved. X-ray doses were limited to the tumour site when animal holders were rotated around their longitudinal axis to 15o and 195o, allowing sequential dose delivery using parallel-opposed tangential beams. Irradiation of subcutaneous melanoma tumour established on the flanks of mice showed regression. CONCLUSION: SARJ enabled delivery of tangential parallel-opposed radiation beams to subcutaneous tumours in up to five mice simultaneously. SARJ allowed high throughput testing of clinically relevant dose delivery using a standard cabinet-style fixed source irradiator. ADVANCES IN KNOWLEDGE: A custom designed jig has been manufactured to fit into conventional cabinet irradiators and is dosimetrically validated to deliver clinically relevant dose distributions to subcutaneous tumours in mice for preclinical studies.

Serial circulating tumour DNA analysis during multimodality treatment of locally advanced rectal cancer: a prospective biomarker study.

OBJECTIVE: For patients with locally advanced rectal cancer (LARC), adjuvant chemotherapy selection following surgery remains a major clinical dilemma. Here, we investigated the ability of circulating tumour DNA (ctDNA) to improve risk stratification in patients with LARC. DESIGN: We enrolled patients with LARC (T3/T4 and/or N+) planned for neoadjuvant chemoradiotherapy. Plasma samples were collected pretreatment, postchemoradiotherapy and 4-10 weeks after surgery. Somatic mutations in individual patient's tumour were identified via massively parallel sequencing of 15 genes commonly mutated in colorectal cancer. We then designed personalised assays to quantify ctDNA in plasma samples. Patients received adjuvant therapy at clinician discretion, blinded to the ctDNA results. RESULTS: We analysed 462 serial plasma samples from 159 patients. ctDNA was detectable in 77%, 8.3% and 12% of pretreatment, postchemoradiotherapy and postsurgery plasma samples. Significantly worse recurrence-free survival was seen if ctDNA was detectable after chemoradiotherapy (HR 6.6; P<0.001) or after surgery (HR 13.0; P<0.001). The estimated 3-year recurrence-free survival was 33% for the postoperative ctDNA-positive patients and 87% for the postoperative ctDNA-negative patients. Postoperative ctDNA detection was predictive of recurrence irrespective of adjuvant chemotherapy use (chemotherapy: HR 10.0; P<0.001; without chemotherapy: HR 22.0; P<0.001). Postoperative ctDNA status remained an independent predictor of recurrence-free survival after adjusting for known clinicopathological risk factors (HR 6.0; P<0.001). CONCLUSION: Postoperative ctDNA analysis stratifies patients with LARC into subsets that are either at very high or at low risk of recurrence, independent of conventional clinicopathological risk factors. ctDNA analysis could potentially be used to guide patient selection for adjuvant chemotherapy.

Development of quality indicators to monitor radiotherapy care for men with prostate cancer: A modified Delphi method.

BACKGROUND AND PURPOSE: Quality indicators (QIs) have been developed for many aspects of prostate cancer care, but are under-developed with regard to radiotherapy treatment. We aimed to develop a valid, relevant and feasible set of core QIs to measure quality of radiotherapy care in men with prostate cancer. MATERIALS AND METHODS: We used a RAND-modified Delphi process to select QIs that were regarded as both important and feasible measures of quality radiotherapy care. This involved two phases: (1) a literature review to identify a list of proposed QIs; and (2) a QI selection process by an expert panel (n = 12) conducted in a series of three rounds: two online questionnaires' and one face-to-face meeting. The RAND criterion identified variation in ratings and determined the level of agreement after each round of voting. RESULTS: A total of 144 candidate QIs, which included measures from pre-treatment to post-treatment and survivorship care were identified. After three rounds of voting, the panel approved a comprehensive set of 17 QIs, with most assessing a process of care (n = 16, 94.1%) and the remaining assessing a health outcome. CONCLUSION: This study developed a core set of 17 QIs which will be used to report from the Prostate Cancer Outcomes Registry-Australia & New Zealand, to monitor the quality of radiotherapy care prostate cancer patients receive.

Development of Indicators to Assess Quality of Care for Prostate Cancer.

BACKGROUND: The development, monitoring, and reporting of indicator measures that describe standard of care provide the gold standard for assessing quality of care and patient outcomes. Although indicator measures have been reported, little evidence of their use in measuring and benchmarking performance is available. A standard set, defining numerator, denominator, and risk adjustments, will enable global benchmarking of quality of care. OBJECTIVE: To develop a set of indicators to enable assessment and reporting of quality of care for men with localised prostate cancer (PCa). DESIGN, SETTING, AND PARTICIPANTS: Candidate indicators were identified from the literature. An international panel was invited to participate in a modified Delphi process. Teleconferences were held before and after each voting round to provide instruction and to review results. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Panellists were asked to rate each proposed indicator on a Likert scale of 1-9 in a two-round iterative process. Calculations required to report on the endorsed indicators were evaluated and modified to reflect the data capture of the Prostate Cancer Outcomes Registry-Australia and New Zealand (PCOR-ANZ). RESULTS AND LIMITATIONS: A total of 97 candidate indicators were identified, of which 12 were endorsed. The set includes indicators covering pre-, intra-, and post-treatment of PCa care, within the limits of the data captured by PCOR-ANZ. CONCLUSIONS: The 12 endorsed quality measures enable international benchmarking on the quality of care of men with localised PCa. Reporting on these indicators enhances safety and efficacy of treatment, reduces variation in care, and can improve patient outcomes. PATIENT SUMMARY: PCa has the highest incidence of all cancers in men. Early diagnosis and relatively high survival rates mean issues of quality of care and best possible health outcomes for patients are important. This paper identifies 12 important measurable quality indicators in PCa care.

Does chronomodulated radiotherapy improve pathological response in locally advanced rectal cancer?

The predominant mode of radiation-induced cell death for solid tumours is mitotic catastrophe, which is in part dependent on sublethal damage repair being complete at around 6 h. Circadian variation appears to play a role in normal cellular division, and this could influence tumour response of radiation treatment depending on the time of treatment delivery. We tested the hypothesis that radiation treatment later in the day may improve tumour response and nodal downstaging in rectal cancer patients treated neoadjuvantly with radiation therapy. Recruitment was by retrospective review of 267 rectal cancer patients treated neoadjuvantly in the Department of Radiation Oncology at the Canberra Hospital between January 2010 and November 2015. One hundred and fifty-five patients met the inclusion criteria for which demographic, pathological and imaging data were collected, as well as the time of day patients received treatment with each fraction of radiotherapy. Data analysis was performed using the Statistical Package R with nonparametric methods of significance for all tests set at p < 0.05. Of the 45 female and 110 male patients, the median age was 64. Seventy-three percent had cT3 disease and there was a mean tumour distance from the anal verge of 7 cm. Time to surgical resection following radiotherapy ranged from 4 to 162 days with a median of 50 days, with a complete pathological response seen in 21% of patients. Patients exhibiting a favourable pathological response had smaller median pre- and postradiotherapy tumour size and had a greater change in tumour size following treatment (p < 0.01). Patients who received the majority of their radiotherapy fractions after 12:00 pm were more likely to show a complete or moderate pathological response (p = 0.035) and improved nodal downstaging. There were also more favourable responses amongst patients with longer time to surgical resection postradiotherapy (p < 0.004), although no relationship was seen between response and tumour distance from the anal verge. Females were less likely to exhibit several of the above responses. Neoadjuvant radiotherapy for locally advanced rectal cancer performed later in the day coupled with a longer time period to surgical resection may improve pathological tumour response rates and nodal downstaging. A prospective study in chronomodulated radiotherapy in this disease is warranted.

Precision Medicine and Pancreatic Cancer: A Gemcitabine Pathway Approach.

OBJECTIVES: There is a need for validated predictive markers of gemcitabine response to guide precision medicine treatment in pancreatic cancer. We previously validated human equilibrative nucleoside transporter 1 as a predictive marker of gemcitabine treatment response using Radiation Therapy Oncology Group 9704. Controversy exists about the predictive value of gemcitabine metabolism pathway biomarkers: deoxycytidine kinase (DCK), ribonucleotide reductase 1 (RRM1), RRM2, and p53R2. METHODS: Radiation Therapy Oncology Group 9704 prospectively randomized 538 patients after pancreatic resection to receive either 5-fluorouracil or gemcitabine. Tumor DCK, RRM1, RRM2, and p53R protein expressions were analyzed using a tissue microarray and immunohistochemistry and correlated with treatment outcome (overall survival and disease-free survival) by unconditional logistic regression analysis. RESULTS: There were 229 patients eligible for analysis from both the 5-fluorouracil and gemcitabine arms. Only RRM2 protein expression, and not DCK, RRM1, or p53R2 protein expression, was associated with survival in the gemcitabine treatment arm. CONCLUSIONS: Despite limited data from other nonrandomized treatment data, our data do not support the predictive value of DCK, RRM1, or p53R2. Efforts should focus on human equilibrative nucleoside transporter 1 and possibly RRM2 as valid predictive markers of the treatment response of gemcitabine in pancreatic cancer.

Alternative cyclin D1 splice forms differentially regulate the DNA damage response.

The DNA damage response (DDR) activates downstream pathways including cell cycle checkpoints. The cyclin D1 gene is overexpressed or amplified in many human cancers and is required for gastrointestinal, breast, and skin tumors in murine models. A common polymorphism in the human cyclin D1 gene is alternatively spliced, resulting in cyclin D1a and D1b proteins that differ in their carboxyl terminus. Cyclin D1 overexpression enhances DNA damage-induced apoptosis. The role of cyclin D1 and the alternative splice form in regulating the DDR is not well understood. Herein cyclin D1a overexpression enhanced the DDR as characterized by induction of γH2AX phosphorylation, the assembly of DNA repair foci, specific recruitment of DNA repair factors to chromatin, and G(2)-M arrest. Cyclin D1 deletion in fibroblasts or small interfering RNA-mediated reduction of endogenous cyclin D1 in colon cancer cells reduced the 5-fluorouracil-mediated DDR. Mechanistic studies showed that cyclin D1a, like DNA repair factors, elicited the DDR when stably associated with chromatin.

Human equilibrative nucleoside transporter 1 levels predict response to gemcitabine in patients with pancreatic cancer.

BACKGROUND & AIMS: The human equilibrative nucleoside transporter (hENT1) protein transports gemcitabine into cells. Small retrospective studies in pancreatic cancer suggest that levels of hENT1 protein or messenger RNA may have prognostic value. We studied the predictive value of hENT1 levels in a cohort of pancreatic adenocarcinoma patients from the large prospective randomized adjuvant treatment trial RTOG9704. METHODS: In RTOG9704, 538 patients were assigned randomly, after surgical resection, to groups that were given either gemcitabine or 5-fluorouracil (5-FU). Immunohistochemistry for hENT1 was performed on a tissue microarray of 229 resected pancreatic tumors from RTOG9704 and scored as having no staining, low staining, or high staining. Associations between hENT1 protein and treatment outcome were analyzed by unconditional logistic regression analysis using the chi-square test and the Cox proportional hazards model. RESULTS: HENT1 expression was associated with overall and disease-free survival in a univariate (hazard ratio [HR], 0.51; 95% confidence interval [CI], 0.29-0.91; P= .02; and HR, 0.57; 95% CI, 0.32-1.00; P= .05) and multivariate model in the group given gemcitabine (HR, 0.40; 95% CI, 0.22-0.75; P= .004; and HR, 0.39; 95% CI, 0.21-0.73; P= .003). hENT1 expression was not associated with survival in the group given 5-FU. CONCLUSIONS: In this prospective randomized trial, hENT1 protein expression was associated with increased overall survival and disease-free survival in pancreatic cancer patients who received gemcitabine, but not in those who received 5-FU. These findings are supported by preclinical data; the gemcitabine transporter hENT1 is therefore a molecular and mechanistically relevant predictive marker of benefit from gemcitabine in patients with resected pancreatic cancer.

Early detection markers in Pancreas Cancer.

The role of early detection in cancer has shown improved survival for certain cancers, including colon cancer, cervical cancer and breast cancer. The possibility for early detection of pancreatic cancer may be realized by an improved understanding of the histology and molecular genetics of precursor lesions and cancerous lesions in pancreatic cancer and the development of sensitive and specific screening tests (both invasive and non-invasive) to detect early pancreatic cancer. The NIH-NCI Early Detection Research Network (EDRN) in Pancreatic Cancer has been focussed on the development and validation of new biomarkers for the detection of early pancreatic cancer. This review will focus on our understanding of the histologic and molecular model of pancreatic carcinogenesis, current strategies and limitations of screening for pancreatic cancer and the development and validation of new biomarkers for the early detection of pancreatic cancer.

The efficacy of hyperbaric oxygen therapy in the treatment of radiation-induced late side effects.

PURPOSE: We investigated the efficacy of hyperbaric oxygen therapy (HBOT) in the management of patients with radiation-induced late side effects, the majority of whom had failed previous interventions. METHODS AND MATERIALS: Of 105 eligible subjects, 30 had either died or were not contactable, leaving 75 who qualified for inclusion in this retrospective study. Patients answered a questionnaire documenting symptom severity before and after treatment (using Radiation Therapy Oncology Group criteria), duration of improvement, relapse incidence, and HBOT-related complications. RESULTS: The rate of participation was 60% (45/75). Improvement of principal presenting symptoms after HBOT was noted in 75% of head-and-neck, 100% of pelvic, and 57% of "other" subjects (median duration of response of 62, 72, and 68 weeks, respectively). Bone and bladder symptoms were most likely to benefit from HBOT (response rate, 81% and 83%, respectively). Fifty percent of subjects with soft tissue necrosis/mucous membrane side effects improved with HBOT. The low response rate of salivary (11%), neurologic (17%), laryngeal (17%), and upper gastrointestinal symptoms (22%) indicates that these were more resistant to HBOT. Relapse incidence was low (22%), and minor HBOT-related complications occurred in 31% of patients. CONCLUSION: Hyperbaric oxygen therapy is a safe and effective treatment modality offering durable relief in the management of radiation-induced osteoradionecrosis either alone or as an adjunctive treatment. Radiation soft tissue necrosis, cystitis, and proctitis also seemed to benefit from HBOT, but the present study did not have sufficient numbers to reliably predict long-term response.

CpG island methylator phenotype is an independent predictor of survival benefit from 5-fluorouracil in stage III colorectal cancer.

PURPOSE: The CpG island methylator phenotype (CIMP) is observed in approximately 30% of colorectal cancer (CRC) cases and is characterized by the concurrent methylation of multiple CpG islands in tumor DNA. This phenotype (CIMP+) is more frequently observed in tumors with proximal location, microsatellite instability, and normal p53. Because it has previously been observed that each of these features is associated with a good survival benefit from 5-fluorouracil (5-FU)-based adjuvant chemotherapy, we investigated in the present study whether CIMP+ has independent predictive value. EXPERIMENTAL DESIGN: CIMP+ status was evaluated in 103 stage III CRCs from patients treated with surgery alone and for an additional 103 cases from patients treated with surgery and adjuvant 5-FU-based chemotherapy. The two cohorts were randomly pair-matched for age, sex, and tumor site, and the median length of follow-up time was 39 months. RESULTS: CIMP+ status predicted survival benefit from 5-FU treatment independently of microsatellite instability and p53 mutation status (relative risk = 0.22; 95% confidence interval, 0.06-0.84; P = 0.027). Unmeasured, high-risk confounding factors could only account for this association if they were unequally distributed between the two patient cohorts by a factor of at least 2-fold. CONCLUSIONS: CIMP+ has independent predictive significance for the survival benefit from 5-FU chemotherapy in CRC. This molecular marker should be incorporated into prospective clinical trials of fluorouracil-based therapies to confirm its clinical value.

Extent of nodal involvement in Stage III colorectal carcinoma: relationship to clinicopathologic variables and genetic alterations.

PURPOSE: Recent evidence from our laboratory suggests that the factors of tumor site, patient gender, microsatellite instability, and mutations are important determinants in the survival benefit associated with adjuvant chemotherapy in Stage III colorectal carcinoma. In the present study we investigated whether these factors, as well as Ki- mutations, were also associated with the extent of nodal involvement in Stage III cancers. METHODS: Nodal involvement was retrospectively evaluated in a series of 645 patients with Stage III colorectal cancer from Sir Charles Gairdner Hospital. The number of involved nodes was correlated with the clinicopathologic features of gender, age, tumor site, and histologic grade, as well as to the genetic alterations of mutation, Ki- mutation, and microsatellite instability. RESULTS: The median number of nodes examined per tumor was 11 (range, 1-53). Forty-nine percent of cases had one or two involved nodes and 51 percent had three or more involved nodes, the latter feature being associated with significantly reduced patient survival. No differences in the extent of nodal involvement were apparent with respect to tumor site, patient gender, or or Ki- mutation status. Tumors from younger patients (P = 0.025) or with poorly differentiated histology (P = 0.007), were associated with significantly higher nodal burden, whereas the microsatellite instability phenotype was associated with less extensive nodal involvement (P = 0.020). Survival benefits from the use of chemotherapy were apparent for both the low and high nodal involvement groups, although the latter seemed to obtain relatively more benefit. Multivariate analysis of patients treated with chemotherapy found that gender, grade, and microsatellite instability, but not nodal involvement, were independently prognostic for survival. CONCLUSION: The extent of nodal involvement in Stage III colorectal cancer is related to patient age, tumor grade, and microsatellite instability status, but not to tumor site, patient gender, or Ki- mutation. These results indicate that differences in metastatic nodal burden cannot explain previously observed site, gender, and mutation differences in the response to chemotherapy.