Detection of metastases in oral squamous cell carcinoma: still a diagnostic impasse

Oral squamous cell carcinoma (OSCC) being the most common malignancy of the oral cavity poses a significant public health problem due its impact on the speech, mastication, taste, swallowing and esthetics. Moreover, the presence of metastasis either regional or distant worsens the prognosis and reduces the survival rate in these patients. This makes it imperative to diagnose metastasis at an early stage to facilitate appropriate therapeutic management to reduce the morbidity and mortality associated with this disease. There have been several modalities that have been developed and in wide-use for recognition of metastasis with their inherent advantages and disadvantages making it a perplexing dilemma to the clinician and surgeon alike. This paper aims to give an insight into the diagnostic workup available for the evaluation of metastasis in patients with OSCC and reinforces the need for further research to develop more accurate methods.

Whole-genome sequencing reveals complex mechanisms of intrinsic resistance to BRAF inhibition

BACKGROUND

BRAF is mutated in ∼42% of human melanomas (COSMIC. http://www.sanger.ac.uk/genetics/CGP/cosmic/) and pharmacological BRAF inhibitors such as vemurafenib and dabrafenib achieve dramatic responses in patients whose tumours harbour BRAF(V600) mutations. Objective responses occur in ∼50% of patients and disease stabilisation in a further ∼30%, but ∼20% of patients present primary or innate resistance and do not respond. Here, we investigated the underlying cause of treatment failure in a patient with BRAF mutant melanoma who presented primary resistance.

METHODS

We carried out whole-genome sequencing and single nucleotide polymorphism (SNP) array analysis of five metastatic tumours from the patient. We validated mechanisms of resistance in a cell line derived from the patient's tumour.

RESULTS

We observed that the majority of the single-nucleotide variants identified were shared across all tumour sites, but also saw site-specific copy-number alterations in discrete cell populations at different sites. We found that two ubiquitous mutations mediated resistance to BRAF inhibition in these tumours. A mutation in GNAQ sustained mitogen-activated protein kinase (MAPK) signalling, whereas a mutation in PTEN activated the PI3 K/AKT pathway. Inhibition of both pathways synergised to block the growth of the cells.

CONCLUSIONS

Our analyses show that the five metastases arose from a common progenitor and acquired additional alterations after disease dissemination. We demonstrate that a distinct combination of mutations mediated primary resistance to BRAF inhibition in this patient. These mutations were present in all five tumours and in a tumour sample taken before BRAF inhibitor treatment was administered. Inhibition of both pathways was required to block tumour cell growth, suggesting that combined targeting of these pathways could have been a valid therapeutic approach for this patient.

Radiobiological impact of planning techniques for prostate cancer in terms of tumor control probability and normal tissue complication probability

Background:

The radiobiological models describe the effects of the radiation treatment on cancer and healthy cells, and the radiobiological effects are generally characterized by the tumor control probability (TCP) and normal tissue complication probability (NTCP).

Aim:

The purpose of this study was to assess the radiobiological impact of RapidArc planning techniques for prostate cancer in terms of TCP and normal NTCP.

Subjects and Methods:

A computed tomography data set of ten cases involving low-risk prostate cancer was selected for this retrospective study. For each case, two RapidArc plans were created in Eclipse treatment planning system. The double arc (DA) plan was created using two full arcs and the single arc (SA) plan was created using one full arc. All treatment plans were calculated with anisotropic analytical algorithm. Radiobiological modeling response evaluation was performed by calculating Niemierko's equivalent uniform dose (EUD)-based Tumor TCP and NTCP values.

Results:

For prostate tumor, the average EUD in the SA plans was slightly higher than in the DA plans (78.10 Gy vs. 77.77 Gy; P = 0.01), but the average TCP was comparable (98.3% vs. 98.3%; P = 0.01). In comparison to the DA plans, the SA plans produced higher average EUD to bladder (40.71 Gy vs. 40.46 Gy; P = 0.03) and femoral heads (10.39 Gy vs. 9.40 Gy; P = 0.03), whereas both techniques produced NTCP well below 0.1% for bladder (P = 0.14) and femoral heads (P = 0.26). In contrast, the SA plans produced higher average NTCP compared to the DA plans (2.2% vs. 1.9%; P = 0.01). Furthermore, the EUD to rectum was slightly higher in the SA plans (62.88 Gy vs. 62.22 Gy; P = 0.01).

Conclusion:

The SA and DA techniques produced similar TCP for low-risk prostate cancer. The NTCP for femoral heads and bladder was comparable in the SA and DA plans; however, the SA technique resulted in higher NTCP for rectum in comparison with the DA technique.

Synthesis of bis(heteroaryl) ketones by removal of benzylic CHR and CO groups

A copper-catalyzed method for synthesis of diaryl ketones (Ar-CO-Ar') through removal of benzylic -CH2-, -CO-, and -CHR- groups from Ar-CO-CXR-Ar' has been discovered. A number of symmetrical and unsymmetrical heterocyclic ketones, which are usually difficult to synthesize, can be prepared in good to excellent yields. This method was applied to the synthesis of the nonsteroidal anti-inflammatory drug suprofen (47% yield over three steps). Based on preliminary mechanistic and kinetic studies, an active Cu/O2 species is proposed to mediate the rearrangement reaction.

Verification of dose calculation algorithms in a multi-layer heterogeneous phantom using films

The development of advanced radiation treatment techniques such as intensity modulated radiation therapy (IMRT) and volumetric intensity modulated arc therapy (VMAT) require more accurate dose calculation algorithms within the treatment planning systems (TPS) considering that the human body is composed of tissues of widely differing radiological properties and the characteristics of a therapeutic radiation treatment beam along a heterogeneous path will be different. The objective of this study was to evaluate the accuracy of 2D-isodose distributions predicted by pencil beam convolution algorithm (PBC) and anisotropic analytic algorithm (AAA) in a heterogeneous slab phantom composed of media equivalent to air, water and bone density. The measurements were done by using the films at multiple depths in the phantom for open field sizes 5 × 5 cm2 and 10 × 10 cm2. The results from this study indicated that the AAA had better agreement with the measurement compared to PBC for both the test field sizes at all selected depths; however, the limitation of AAA in predicting doses within and beyond low-density medium was observed, especially for a smaller field size (up to 32.7% and 34.0% for AAA and PBC, respectively). Furthermore, discrepancies up to -4.8% for AAA and -14.6% for PBC was seen in the high-density medium as well. Dose prediction errors by the AAA and PBC were more pronounced for a smaller test field size, especially in the low-density medium.

KEYWORDS

IMRT, dose calculation algorithms, Anisotropic Analytical Algorithm (AAA), Pencil Beam Convolution (PBC), Varian's Eclipse treatment planning system.