Treatment response to neoadjuvant chemoradiotherapy among patients with locally advanced rectal cancer undergoing radical resection is an early surrogate marker and correlate to oncologic outcomes. These data provide guidance with response-stratified oncologic benchmarks for comparisons of novel treatment strategies.
Purpose
We evaluated clinical features and survival outcomes among patients with signet ring and mucinous histologies of colorectal adenocarcinoma using data from the National Cancer Data Base (NCDB).
Methods
Patients aged 18–90 years with colorectal adenocarcinoma diagnosed between 1998 and 2002 were identified from the NCDB. Site-stratified (colon vs rectum) survival analysis was performed using multivariate relative survival adjusted for multiple clinicopathologic and treatment variables.
Results
The study included 244,794 patients: 25,546 (10%) with mucinous, 2,260 (1%) with signet ring, and 216,988 (89%) with nonmucinous, non–signet ring adenocarcinoma. Mucinous and signet ring cancers were more frequently right-sided (60% and 62%, respectively) than were nonmucinous, non–signet ring adenocarcinomas (42%, P < .001). Signet ring histology was associated with a higher stage (P < .001), and 77.2% of signet ring tumors were high-grade lesions, compared with 20% of mucinous and 17% of non–signet ring, nonmucinous adenocarcinomas (P < .001). After adjustment for covariates, signet ring histology was independently associated with higher risk of death (HR 1.42, 95% confidence interval [CI] 1.33-1.51, and HR 1.57, CI 1.38-1.77, for tumors located in the colon and rectum, respectively). Mucinous tumors of the rectum (HR 1.22, CI 1.16-1.29), but not the colon (HR 1.03, CI 1.00-1.06), were associated with increased risk of death.
Conclusion
Signet ring cell adenocarcinomas of the colon and rectum and mucinous adenocarcinomas of the rectum are associated with poorer survival. These aggressive histologic variants of colorectal adenocarcinoma should be targeted for research initiatives to improve outcomes.
Breast conservation therapy after neoadjuvant chemotherapy results in acceptably low rates of LRR and IBTR in appropriately selected patients, even those with T3 or T4 disease. Advanced nodal involvement at diagnosis, residual tumor larger than 2 cm, multifocal residual disease, and lymphovascular space invasion predict higher rates of LRR and IBTR.
KIT gain of function mutations play an important role in the pathogenesis of gastrointestinal stromal tumors (GISTs). Imatinib is a selective tyrosine kinase inhibitor of ABL, platelet-derived growth factor receptor (PDGFR), and KIT and represents a new paradigm of targeted therapy against GISTs. Here we report for the first time that, after imatinib treatment, an additional specific and novel KIT mutation occurs in GISTs as they develop resistance to the drug. We studied 12 GIST patients with initial near-complete response to imatinib. Seven harbored mutations in KIT exon 11, and 5 harbored mutations in exon 9. Within 31 months, six imatinib-resistant rapidly progressive peritoneal implants (metastatic foci) developed in five patients. Quiescent residual GISTs persisted in seven patients. All six rapidly progressive imatinib-resistant implants from five patients show an identical novel KIT missense mutation, 1982T3 C, that resulted in Val654Ala in KIT tyrosine kinase domain 1. This novel mutation has never been reported before, is not present in pre-imatinib or post-imatinib residual quiescent GISTs, and is strongly correlated with imatinib resistance. Allelic-specific sequencing data show that this new mutation occurs in the allele that harbors original activation mutation of KIT.
Our data suggest that the three-step strategy of preoperative induction chemotherapy followed by chemoradiotherapy resulted in substantial pathologic response that resulted in durable survival time. This strategy is worthy of a direct comparison with postoperative adjuvant chemoradiotherapy.
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