Volumetric image guidance for intravaginal brachytherapy: A dosimetric and clinical study.

Background: The present retrospective dosimetric and clinical study aims to explore the subset of patients who will benefit from volumetric image guidance in intravaginal brachytherapy (IVBT). Materials and Methods: Sixty-three consecutive patients who underwent IVBT using single-channel intravaginal cylinder were analyzed. The most common IVBT dose protocol was 1100 cGy in two fractions (with external beam radiotherapy [EBRT]) and 2200 cGy in four fractions (when used alone). The factors affecting the dose to organs at risk (OARs) (such as treated length, orientation of applicator, EBRT) and target volume were analyzed. Local control rate and late toxicities were reported. Results: There was a statistically significant increase in equivalent dose at 2 Gy per fraction (EQD2) doses of all OARs with the addition of EBRT. In 39.4%, EQD2 D2cc dose of rectum was more than 65 Gy. There was a statistically significant positive correlation with increasing treated length in D5cc (Gy) of rectum and D5cc (Gy) of urethra (Pearson's correlation coefficient of 0.375, P = 0.002 and Pearson's correlation coefficient of 0.394, P = 0.001, respectively). There was a statistically significant increase in D2cc and D5cc of rectum with posterior orientation. Air gaps were noted in 81% of applications. Median duration of follow-up was 30 months. One patient had vaginal recurrence in lower third of vagina. One patient was recorded with grade 2 hemorrhagic radiation proctitis. Conclusion: Computed tomography (CT)-based volumetric planning is an effective method to evaluate doses to OARs and confirm the adequacy of dose coverage, and we recommend routine use of the same. Image guidance is most beneficial in patients being treated with a combination of IVBT and EBRT, posterior orientation, and those who are treated for the entire length of vagina.

RhoC in association with TET2/WDR5 regulates cancer stem cells by epigenetically modifying the expression of pluripotency genes.

Emerging evidence illustrates that RhoC has divergent roles in cervical cancer progression where it controls epithelial to mesenchymal transition (EMT), migration, angiogenesis, invasion, tumor growth, and radiation response. Cancer stem cells (CSCs) are the primary cause of recurrence and metastasis and exhibit all of the above phenotypes. It, therefore, becomes imperative to understand if RhoC regulates CSCs in cervical cancer. In this study, cell lines and clinical specimen-based findings demonstrate that RhoC regulates tumor phenotypes such as clonogenicity and anoikis resistance. Accordingly, inhibition of RhoC abrogated these phenotypes. RNA-seq analysis revealed that RhoC over-expression resulted in up-regulation of 27% of the transcriptome. Further, the Infinium MethylationEPIC array showed that RhoC over-expressing cells had a demethylated genome. Studies divulged that RhoC via TET2 signaling regulated the demethylation of the genome. Further investigations comprising ChIP-seq, reporter assays, and mass spectrometry revealed that RhoC associates with WDR5 in the nucleus and regulates the expression of pluripotency genes such as Nanog. Interestingly, clinical specimen-based investigations revealed the existence of a subset of tumor cells marked by RhoC+/Nanog+ expression. Finally, combinatorial inhibition (in vitro) of RhoC and its partners (WDR5 and TET2) resulted in increased sensitization of clinical specimen-derived cells to radiation. These findings collectively reveal a novel role for nuclear RhoC in the epigenetic regulation of Nanog and identify RhoC as a regulator of CSCs. The study nominates RhoC and associated signaling pathways as therapeutic targets.