Pathological assessment of post-treatment gastrointestinal and hepatic resection specimens

Potential Clinical Utility of a Targeted Circulating Tumor DNA Assay in Esophageal Adenocarcinoma

Objective

To explore the clinical utility of circulating tumor DNA (ctDNA) in esophageal adenocarcinoma (EAC) by developing a cost-effective and rapid technique utilising targeted amplicon sequencing (TA-seq).

Summary background data

Emerging evidence suggests that levels of ctDNA in the blood can be used to monitor treatment response and in the detection of disease recurrence in various cancer types. Current staging modalities for EAC such as computerised tomography of the chest/abdomen/pelvis (CT) and positron emission tomography (PET) do not reliably detect occult micro-metastatic disease, the presence of which signifies a poor prognosis. After curative-intent treatment, some patients are still at high risk of recurrent disease, and there is no widely accepted optimal surveillance tool for patients with EAC.

Methods

Sixty-two patients with EAC were investigated for the presence of ctDNA using a tumor-informed approach. We designed a custom TA-seq panel of target specific primers covering mutational foci in 9 of the most commonly mutated genes in EAC. Serial blood samples were taken before and after neoadjuvant treatment (NAT), and during surveillance.

Results

Somatic mutations were detected in pre-treatment biopsy samples of 55 out of 62 (89%) EAC patients. Mutations in TP53 (80%) were the most common. Out of these 55 patients, 20 (36%) had detectable ctDNA at baseline. The majority (90%) of patients with detectable ctDNA had either locally advanced tumors, nodal involvement or metastatic disease. In patients with locally advanced tumors, disease free survival (DFS) was more accurately stratified using pre-treatment ctDNA status (HR 4.34 [95% CI 0.93 - 20.21]; p = 0.05) compared to nodal status on PET-CT. In an exploratory subgroup analysis, patients who are node negative but ctDNA positive have inferior DFS (HR 11.71 [95% CI 1.16-118.80] p = 0.04). In blood samples taken before and following NAT, clearance of ctDNA after NAT was associated with a favourable response to treatment. Furthermore, patients who are ctDNA positive during post-treatment surveillance are at high risk of relapse.

Conclusions

Our study shows that ctDNA has potential to provide additional prognostication over conventional staging investigation such as CT and PET. It may also have clinical utility in the assessment of response to NAT and as a biomarker for the surveillance of recurrent disease.

The spectrum of histopathological changes encountered in pancreatectomy specimens after neoadjuvant chemoradiation, including subtle and less-well-recognised changes

Preoperative (neoadjuvant) chemoradiation therapy/treatment (NCRT) is emerging as an important treatment modality in borderline resectable pancreatic ductal adenocarcinoma (PDAC). The constellation of histopathological changes secondary to chemoradiation is diverse and has been well documented, particularly in other gastrointestinal organs such as the oesophagus and colorectum. However, the histological changes specific to the pancreas have not been fully characterised and described. This review aims to provide a detailed catalogue of histological features associated with NCRT-treated PDAC and highlight any subtle, less-recognised changes.

Controversies in the pathological assessment of colorectal cancer

Pathologic assessment of colorectal cancer specimens plays an essential role in patient management, informing prognosis and contributing to therapeutic decision making. The tumor-node-metastasis (TNM) staging system is a key component of the colorectal cancer pathology report and provides important prognostic information. However there is significant variation in outcome of patients within the same tumor stage. Many other histological features such as tumor budding, vascular invasion, perineural invasion, tumor grade and rectal tumor regression grade that may be of prognostic value are not part of TNM staging. Assessment of extramural tumor deposits and peritoneal involvement contributes to TNM staging but there are some difficulties with the definition of both of these features. Controversies in colorectal cancer pathology reporting include the subjective nature of some of the elements assessed, poor reporting rates and reproducibility and the need for standardized examination protocols and reporting. Molecular pathology is becoming increasingly important in prognostication and prediction of response to targeted therapies but accurate morphology still has a key role to play in colorectal cancer pathology reporting.

A simplified tumor regression grade correlates with survival in locally advanced rectal carcinoma treated with neoadjuvant chemoradiotherapy

BACKGROUND

Locally advanced rectal cancer is frequently treated with neoadjuvant chemoradiotherapy to reduce local recurrence and possibly improve survival. The tumor response to chemoradiotherapy is variable and may influence the prognosis after surgery. This study assessed tumor regression and its influence on survival in patients with rectal cancer treated with chemoradiotherapy followed by curative surgery.

METHODS

One hundred twenty-six patients with locally advanced rectal cancer (T3/T4 or N1/N2) were treated with chemoradiotherapy followed by total mesorectal excision. Patients received long-course radiotherapy (50 Gy in 25 fractions) in combination with 5-flourouracil over 5 weeks. By means of a standardized approach, tumor regression was graded in the resection specimen using a 3-point system related to tumor regression grade (TRG): complete or near-complete response (TRG1), partial response (TRG2), or no response (TRG3).

RESULTS

The 5-year disease-free survival was 72% (median follow-up 37 months), and 7% of patients had local recurrence. Chemoradiotherapy produced downstaging in 60% of patients; 21% of patients experienced TRG1. TRG1 correlated with a pathological T0/1 or N0 status. Five-year disease-free survival after chemoradiotherapy and surgery was significantly better in TRG1 patients (100%) compared with TRG2 (71%) and TRG3 (66%) (P = .01).

CONCLUSION

Tumor regression grade measured on a 3-point system predicts outcome after chemoradiotherapy and surgery for locally advanced rectal cancer.