Borderline resectable pancreatic cancer: conceptual evolution and current approach to image-based classification

Background

Diagnostic imaging plays a critical role in the initial diagnosis and therapeutic monitoring of pancreatic adenocarcinoma. Over the past decade, the concept of 'borderline resectable' pancreatic cancer has emerged to describe a distinct subset of patients existing along the spectrum from resectable to locally advanced disease for whom a microscopically margin-positive (R1) resection is considered relatively more likely, primarily due to the relationship of the primary tumor with surrounding vasculature.

Materials and methods

This review traces the conceptual evolution of borderline resectability from a radiological perspective, including the debates over the key imaging criteria that define the thresholds between resectable, borderline resectable, and locally advanced or metastatic disease. This review also addresses the data supporting neoadjuvant therapy in this population and discusses current imaging practices before and during treatment.

Results

A growing body of evidence suggests that the borderline resectable group of patients may particularly benefit from neoadjuvant therapy to increase the likelihood of an ultimately margin-negative (R0) resection. Unfortunately, anatomic and imaging criteria to define borderline resectability are not yet universally agreed upon, with several classification systems proposed in the literature and considerable variance in institution-by-institution practice. As a result of this lack of consensus, as well as overall small patient numbers and lack of established clinical trials dedicated to borderline resectable patients, accurate evidence-based diagnostic categorization and treatment selection for this subset of patients remains a significant challenge.

Conclusions

Clinicians and radiologists alike should be cognizant of evolving imaging criteria for borderline resectability given their profound implications for treatment strategy, follow-up recommendations, and prognosis.

Phase II cisplatin, irinotecan, cetuximab and concurrent radiation therapy followed by surgery for locally advanced esophageal cancer

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Background: Weekly irinotecan, cisplatin, and concurrent radiation therapy is a well-tolerated, active regimen in locally advanced esophageal cancer. (Ilson. JCO 2003) Cetuximab, an EGFR inhibitor, is a potent radiation sensitizer in head and neck cancer. (Bonner. Proc ASCO 2004) Methods: In this phase II trial, patients (pts) with T2–4N0–1M0–1A esophageal adenocarcinoma (A) or squamous cell carcinoma (S) receive 5040 cGy/28 fractions of radiation therapy (RT) and concurrent weekly cisplatin 30mg/m2 plus irinotecan 65 mg/m2 on weeks 1, 2, 4, and 5, followed by surgery 4–8 weeks after completion of RT. Additionally, pts receive weekly infusions of cetuximab 250 mg during RT, up to one week before surgery, and for 6 months following surgery. Results: Seventeen pts have been entered: male: female = 14:3, median age 54, ECOG PS 0:1 = 6:11, A:S = 17:0, stage IIA:IIB:III:IVA = 6:1:8:2, tumor location-esophagus-mid:lower:gastroesophageal junction = 1:4:12, >10% weight loss-yes:no = 8:9. Of 17 pts entered, 15 pts have proceeded to surgery, 1 pt died from Aspergillus infection resulting in respiratory failure and sepsis, and 1 pt is pending surgery. Of the 15 pts who underwent surgery, 2 (13%) had a complete pathologic response; pathologic stage for other pts: 0 = 1, I = 3, IIA = 3, IIB = 1, III = 4, IV = 1. Grade III/IV toxicity (17 pts) was: diarrhea 9 pts, neutropenia 9 pts, febrile neutropenia 5 pts, anorexia 5 pts, vomiting 4 pts, fatigue 3 pts, mucositis 1 pt. Chemotherapy dose attenuation was required for diarrhea in 5 pts, for neutropenia in 4 pts, and for folliculitis in 1 pt. One patient was removed from study during week 6 for prolonged diarrhea/ dehydration. Due to the 2-step design of the trial, accrual is on hold pending a 3rd required pathologic CR in the first 17 patients. Conclusions: Compared to other trials of irinotecan, cisplatin, radiation therapy, and surgery in similar groups of esophageal cancer patients, early results for this combination with cetuximab suggest a lower complete response rate and higher overall toxicity. Additional data will be available at ASCO. Supported by Bristol-Myers Squibb.

No significant financial relationships to disclose.

Perioperative radiotherapy for cancer of the esophagus

Carcinomas of the esophagus represent on average about 1% to 2% of all malignant tumors. The incidence shows extreme regional differences, reflecting the established environmental and acquired risk factors for cancer of the esophagus. There has been a major shift in tumor location and histology over the last decades, with the lower third/gastroesophageal junction becoming the most common location and adenocarcinoma the most common histology in white males. There has been a striking improvement in surgical resection rates and operative mortality; however, the curative potential of surgery is likely to be highest in early-stage disease. The poor prognosis for locally advanced tumors motivated the search for multimodal approaches to improve results. While neither perioperative radiotherapy nor perioperative chemotherapy alone have significantly improved survival rates, combined radiochemotherapy, used as neoadjuvant or definitive therapy, appears more promising. For patients with advanced tumors or extensive nodal involvement, first principles and extrapolation from other tumors of the gastrointestinal tract suggest that a combination of chemotherapy and radiation is likely to be of benefit, as compared to surgery alone. As this treatment is difficult to tolerate in the postoperative setting, neoadjuvant approaches have been emphasized. Although there are promising data, and preoperative chemoradiation is widely utilized, we do not consider the benefit of this approach to have been proven unequivocally. Future progress in the treatment of esophageal cancer may require that systemic therapy be improved to the point where occult metastatic disease can be controlled, enabling the local control provided by surgery and radiation to lead to improved survival.

Interaction of the protein kinase Raf-1 with 14-3-3 proteins

Members of a family of highly conserved proteins, termed 14-3-3 proteins, were found by several experimental approaches to associate with Raf-1, a central component of a key signal transduction pathway. Optimal complex formation required the amino-terminal regulatory domain of Raf-1. The association of 14-3-3 proteins and Raf-1 was not substantially affected by the activation state of Raf.

Nuclear assembly of polyomavirus capsids in insect cells expressing the major capsid protein VP1

Polyomavirus normally assembles in the nucleus of infected mouse cells. Sf9 insect cells expressing the polyomavirus major capsid protein VP1 were examined by electron microscopy. Capsidlike particles of apparently uniform size were found in the nucleus. Immunogold electron microscopy demonstrated abundant VP1 in the cytoplasm which was not assembled into any recognizable higher-order structure. Cytoplasmic VP1 assembled after the cells were treated with the calcium ionophore ionomycin. Purified VP1 aggregates were shown by negative staining and cryoelectron microscopy to consist predominantly of particles similar to the empty T = 7 viral capsid. Thus, polyomavirus VP1 can assemble in vivo into capsids independent of other viral proteins or DNA. Nuclear assembly may result from increased available calcium in this subcellular compartment.

The t-unique coding domain is important to the transformation maintenance function of the simian virus 40 small t antigen

The small t antigen (t) of simian virus 40, a 174-amino-acid-containing protein, when present together with the other early viral protein, large T antigen (T), plays an important role in the maintenance of simian virus 40-induced neoplastic phenotype in certain cells. Indeed, each protein functions in a complementary manner in this process. The t coding unit is composed of two segments, a 5' region of 246 nucleotides which is identical to that of the corresponding 5' region of the T coding unit and a 3' segment of 276 nucleotides which is unique. Two mutant, t-encoding genomes, one bearing a missense and the other a nonsense mutation at the same point in the t-unique coding region were constructed in vitro and found to be defective in their ability to dissolve the actin cytoskeleton of rat fibroblasts and to complement T in the growth of mouse fibroblasts in soft agar. Therefore, the unique segment of the t gene encodes a portion of the t molecule which is essential to its transformation maintenance function.