A study for evaluating clinical relevance of circulating cell-free DNA in cervical cancer.

Introduction: Recent techniques available for the detection of cervical cancer (CC) are highly invasive and costly, which makes it a rate-limiting step toward early diagnosis of this fatal disease. Evaluation of circulating cell-free DNA (ccfDNA) through liquid biopsy is a minimally invasive and cost-effective method that may serve as a unique tumor marker for early detection, treatment monitoring, the status of residual disease, and distant tumor metastasis in CC patients. Materials and Methods: In this study, initially, ccfDNA was measured in serum samples from 11 histopathologically proven cervix carcinoma patients and 8 controls. On successful screening, it was further extended to 2 more patients with a series of serum samples extracted at 3 different phases of the concurrent chemoradiotherapy (i.e., before, during, and after 6 months of follow-up). Results: Agarose gel electrophoresis profile for ccfDNA of CC patients showed that of 11 patients, 4 patients had a comparatively higher tumor burden (ccfDNA) than the other 7 patients. Notably, during concurrent chemoradiotherapy, ccfDNA load disappeared and, after 6 months of follow-up, appeared back due to distant metastasis. Conclusion: Hence, we propose that this method could be an affordable and reliable way to diagnose/screen CC.

Underdosing of the maxillary sinus for small fields used in newer radiotherapy techniques: Comparison of thermoluminescent dosimeter and Monte Carlo data.

AIMS: To evaluate the underdosing of the maxillary sinus at its distal end produced by air cavity in the path of the 6 MV photon beam. MATERIALS AND METHODS: A cubic solid water slab phantom of dimensions 18 cm × 18 cm × 18 cm with 4 cm × 4 cm × 4 cm air cavity 3 cm away from its anterior surface was used in this study. The percentage depth dose (PDD) for 6 MV X-rays along the central axis of the cubical air cavity was measured using thermoluminescent dosimeter-100 chips. The EGSnrc/DOSXYZnrc Monte Carlo (MC) code was used to estimate the PDD values in both homogeneous and inhomogeneous conditions. The dose data were generated for 1 cm × 1 cm, 2 cm × 2 cm, 3 cm × 3 cm, and 5 cm × 5 cm field sizes. RESULTS: Average percentage dose reductions at 1 mm beyond the distal surface of the maxillary sinus for the field sizes 1 × 1, 2 × 2, and 3 × 3 cm2 are 42.4%, 39.5%, and 29.4%, respectively. However, for 5 cm × 5 cm field size, there is a dose enhancement (i.e., overdosing) at 1 mm from the distal surface of the maxillary sinus and the average percentage dose enhancement is 5.9%. Also, beyond 1 cm from the air-water interface, there is dose enhancement for all the field sizes. CONCLUSION: This study showed that the significant dose reduction occurs near the air-water interface for the treatment techniques using small photon fields such as intensity-modulated radiotherapy or other newer techniques. MC-based treatment planning calculation predicts realistic dose distribution while using small photon fields in the treatment of maxillary sinus.