Multiregion ultra-deep sequencing reveals early intermixing and variable levels of intratumoral heterogeneity in colorectal cancer.

Intratumor heterogeneity (ITH) contributes to cancer progression and chemoresistance. We sought to comprehensively describe ITH of somatic mutations, copy number, and transcriptomic alterations involving clinically and biologically relevant gene pathways in colorectal cancer (CRC). We performed multiregion, high-depth (384× on average) sequencing of 799 cancer-associated genes in 24 spatially separated primary tumor and nonmalignant tissues from four treatment-naïve CRC patients. We then used ultra-deep sequencing (17 075× on average) to accurately verify the presence or absence of identified somatic mutations in each sector. We also digitally measured gene expression and copy number alterations using NanoString assays. We identified the subclonal point mutations and determined the mutational timing and phylogenetic relationships among spatially separated sectors of each tumor. Truncal mutations, those shared by all sectors in the tumor, affected the well-described driver genes such as APC, TP53, and KRAS. With sequencing at 17 075×, we found that mutations first detected at a sequencing depth of 384× were in fact more widely shared among sectors than originally assessed. Interestingly, ultra-deep sequencing also revealed some mutations that were present in all spatially dispersed sectors, but at subclonal levels. Ultra-high-depth validation sequencing, copy number analysis, and gene expression profiling provided a comprehensive and accurate genomic landscape of spatial heterogeneity in CRC. Ultra-deep sequencing allowed more sensitive detection of somatic mutations and a more accurate assessment of ITH. By detecting the subclonal mutations with ultra-deep sequencing, we traced the genomic histories of each tumor and the relative timing of mutational events. We found evidence of early mixing, in which the subclonal ancestral mutations intermixed across the sectors before the acquisition of subsequent nontruncal mutations. Our findings also indicate that different CRC patients display markedly variable ITH, suggesting that each patient's tumor possesses a unique genomic history and spatial organization.

Addressing the needs of colorectal cancer survivors: current strategies and future directions.

Colorectal cancer (CRC) is one of the three topmost common cancers in men and the second most common cancer in women worldwide. With current advances in the medical and surgical treatment of CRC, care has slowly transformed to curative treatment. With these advances, CRC survivors are increasing in numbers and these patients have a unique range of medical, physical and psychological needs that require regular follow-up. In 2006, the Institute of Medicine recommended that cancer survivors who are completing primary treatment receive a survivorship care plan. There are many different programs of different complexity that are implemented for CRC survivors. This review outlines the needs of CRC survivors, the current surveillance techniques used in the continuing care of patients with CRC after curative treatment and the evidence behind these strategies.

High-depth sequencing of over 750 genes supports linear progression of primary tumors and metastases in most patients with liver-limited metastatic colorectal cancer.

BACKGROUND: Colorectal cancer with metastases limited to the liver (liver-limited mCRC) is a distinct clinical subset characterized by possible cure with surgery. We performed high-depth sequencing of over 750 cancer-associated genes and copy number profiling in matched primary, metastasis and normal tissues to characterize genomic progression in 18 patients with liver-limited mCRC. RESULTS: High depth Illumina sequencing and use of three different variant callers enable comprehensive and accurate identification of somatic variants down to 2.5% variant allele frequency. We identify a median of 11 somatic single nucleotide variants (SNVs) per tumor. Across patients, a median of 79.3% of somatic SNVs present in the primary are present in the metastasis and 81.7% of all alterations present in the metastasis are present in the primary. Private alterations are found at lower allele frequencies; a different mutational signature characterized shared and private variants, suggesting distinct mutational processes. Using B-allele frequencies of heterozygous germline SNPs and copy number profiling, we find that broad regions of allelic imbalance and focal copy number changes, respectively, are generally shared between the primary tumor and metastasis. CONCLUSIONS: Our analyses point to high genomic concordance of primary tumor and metastasis, with a thick common trunk and smaller genomic branches in general support of the linear progression model in most patients with liver-limited mCRC. More extensive studies are warranted to further characterize genomic progression in this important clinical population.

Biofeedback is an effective treatment for patients with dyssynergic defaecation.

INTRODUCTION: Constipation is a common affliction affecting the general population, with dyssynergic defaecation accounting for a large proportion of tertiary referrals. We sought to review the results of our patients with dyssynergic defaecation treated with biofeedback therapy in order to determine its efficacy. METHODS: All patients who were referred to the anorectal physiology laboratory of our tertiary unit for biofeedback therapy for dyssynergic defaecation were reviewed. Patients diagnosed with secondary constipation and slow-transit constipation were excluded. A defaecating proctogram was used to exclude anatomical abnormalities causing outlet obstruction. Patients underwent a four-session, structured biofeedback exercise programme under the supervision of trained nurses. The effectiveness of biofeedback treatment was assessed using the validated Eypasch's Gastrointestinal Quality of Life Index (GIQLI). RESULTS: 226 patients (85 male, 141 female; median age 48 years) underwent biofeedback treatment. Post treatment, improvement was observed in the overall total score of the GIQLI, with gastrointestinal symptom (68.6%), emotion (61.0%) and physical function (57.9%) components showing the most improvement. These improvements were also reflected in the mean scores of each component and the mean total score. All components, except for social function and medication, and the overall total score showed significant improvement post treatment. At the one-year follow-up, 160 (71%) patients reported that improvements were maintained. CONCLUSION: Biofeedback is an effective treatment for patients with dyssynergic defaecation. Patients with chronic constipation not improved by fibre and laxatives should be referred to a tertiary centre with facilities for further anorectal physiological assessment.