Impact of bowel space contouring variability on radiation dose and volume assessments in treatment planning for gynaecologic cancers

INTRODUCTION

Correlations between radiation dose/volume measures and small bowel (SB) toxicity are inconsistent in the medical literature. We assessed the impact of inter-provider variation in bowel bag contouring technique on estimates of radiation dose received by the SB during pelvic radiotherapy.

METHODS

Ten radiation oncologists contoured rectum, bladder and bowel bags on treatment planning computed tomography (CT) scans of two patients receiving adjuvant radiation for endometrial cancer. A radiation plan was generated for each patient and used to determine the radiation dose/volume for each organ. Kappa statistics were applied to assess the inter-provider contouring agreement, and Levene test evaluated the homogeneity of variance for radiation dose/volume metrics, including the V45Gy (cm3 ).

RESULTS

The bowel bag showed greater variation in radiation dose/volume estimates compared to the bladder and rectum. The V45Gy ranged from 163 to 384 cm3 for data set A and 109 to 409 cm3 for dataset B. Kappa values were 0.82/0.83, 0.92/0.92 and 0.94/0.86 for the bowel bag, rectum, and bladder on data sets A/B, demonstrating lower inter-provider agreement for bowel bag compared with bladder and rectum.

CONCLUSION

Inter-provider contouring variability is more significant for the bowel bag than the rectum and bladder, with an associated greater variability in dose and volume estimates during radiation planning.

Impact of bowel space contouring variability on radiation dose and volume assessments in treatment planning for gynaecologic cancers

Introduction

Correlations between radiation dose/volume measures and small bowel (SB) toxicity are inconsistent in the medical literature. We assessed the impact of inter‐provider variation in bowel bag contouring technique on estimates of radiation dose received by the SB during pelvic radiotherapy.

Methods

Ten radiation oncologists contoured rectum, bladder and bowel bags on treatment planning computed tomography (CT) scans of two patients receiving adjuvant radiation for endometrial cancer. A radiation plan was generated for each patient and used to determine the radiation dose/volume for each organ. Kappa statistics were applied to assess the inter‐provider contouring agreement, and Levene test evaluated the homogeneity of variance for radiation dose/volume metrics, including the V45Gy (cm3).

Results

The bowel bag showed greater variation in radiation dose/volume estimates compared to the bladder and rectum. The V45Gy ranged from 163 to 384 cm3 for data set A and 109 to 409 cm3 for dataset B. Kappa values were 0.82/0.83, 0.92/0.92 and 0.94/0.86 for the bowel bag, rectum, and bladder on data sets A/B, demonstrating lower inter‐provider agreement for bowel bag compared with bladder and rectum.

Conclusion

Inter‐provider contouring variability is more significant for the bowel bag than the rectum and bladder, with an associated greater variability in dose and volume estimates during radiation planning.

Efficacy of nelfinavir as monotherapy in refractory adenoid cystic carcinoma: Results of a phase II clinical trial

BACKGROUND

Adenoid cystic carcinomas (ACCs) are malignant salivary gland tumors noteworthy for high rates of late failure with limited salvage therapy options. We have previously shown increased Akt signaling is common in ACC and the human immunodeficiency virus (HIV) protease inhibitor nelfinavir (NFV) inhibits in vitro tumor growth by suppressing Akt signaling. This phase II trial was conducted to determine progression-free survival in response to NFV in patients with recurrent/endstage ACC who have failed standard therapies.

METHODS

Eligible patients had recurrent or end-stage ACC and measureable disease per Response Evaluation Criteria in Solid Tumors (RECIST) criteria. NFV was provided at 1250 mg twice daily.

RESULTS

Among 15 trial participants, median progression-free survival was 5.5 months (lower 95% bound 4.4 months). No patient achieved a RECIST partial or complete response to therapy.

CONCLUSION

NFV monotherapy does not result in a meaningful improvement in clinical outcomes among patients with recurrent ACC.

Impaired PTPN13 phosphatase activity in spontaneous or HPV-induced squamous cell carcinomas potentiates oncogene signaling through the MAP kinase pathway

Human papillomaviruses (HPVs) are a causative factor in over 90% of cervical and 25% of head and neck squamous cell carcinomas (HNSCCs). The C terminus of the high-risk HPV 16 E6 oncoprotein physically associates with and degrades a non-receptor protein tyrosine phosphatase (PTPN13), and PTPN13 loss synergizes with H-Ras(V12) or ErbB2 for invasive growth in vivo. Oral keratinocytes that have lost PTPN13 and express H-Ras(V12) or ErbB2 show enhanced Ras/RAF/MEK/Erk signaling. In co-transfection studies, wild-type PTPN13 inhibited Ras/RAF/MEK/Erk signaling in HEK 293 cells that overexpress ErbB2, EGFR or H-Ras(V12), whereas an enzymatically inactive PTPN13 did not. Twenty percent of HPV-negative HNSCCs had PTPN13 phosphatase mutations that did not inhibit Ras/RAF/MEK/Erk signaling. Inhibition of Ras/RAF/MEK/Erk signaling using MEK inhibitor U0126 blocked anchorage-independent growth in cells lacking PTPN13. These findings show that PTPN13 phosphatase activity has a physiologically significant role in regulating MAP kinase signaling.

The role of human papillomavirus 16 E6 in anchorage-independent and invasive growth of mouse tonsil epithelium

OBJECTIVE

To provide a manipulatable system to study the mechanism of human papillomavirus 16 (HPV16) E6-related transformation of an epithelial cell type affected by HPV16 in humans.

DESIGN

Biochemical and physiological studies of mouse tonsil epithelial cells (MTECs) transformed with HPV16 oncogenes plus H-ras in vitro and in vivo.

SETTING

Basic research laboratory.

PARTICIPANTS

C57BL/6 mice.

INTERVENTIONS

Transduction of the HPV16 oncogenes E6 and E7 in retroviral vectors into MTECs with isolation of multiple individual clones that expressed E6, E7, or both alone or in conjunction with H-ras.

MAIN OUTCOME MEASURES

Growth in culture, anchorage-independent growth, and growth in immune competent, syngeneic mice.

RESULTS

The MTECs that expressed E6 degraded p53 by a mechanism that is inhibited by proteasomal blockade. Although normal MTECs senesced after 20 population doublings, E6 alone or in combination with E7 was sufficient to immortalize MTECs beyond 25 population doublings, lower their population-doubling time, and permit anchorage-independent growth. However, only MTECs that express E6 plus H-ras or E6/E7 plus H-ras formed invasive tumors in immune competent, syngeneic mice at orthotopic intraoral and subdermal sites.

CONCLUSIONS

We found that HPV16 E6 and E7 alone are not sufficient for invasive growth. However, the synergistic activity of H-ras and E6 was sufficient to result in invasive growth.