Toward personalized dose-prescription in locally advanced non-small cell lung cancer: Validation of published normal tissue complication probability models

PURPOSE

To identify published normal tissue complication probability (NTCP) models suitable for patient-specific dose-prescription in locally advanced non-small cell lung cancer (LA-NSCLC) through in-house validation.

MATERIAL AND METHODS

From eight previously published candidate NTCP models (≥grade 2 acute esophagitis and radiation pneumonitis; AE2, RP2), patient-specific dose-responses were calculated using model variables and fractionation-corrected doses for 241 LA-NSCLC patients treated with chemo-IMRT to 50-80 Gy@1.8-2.0 Gy between 2004 and 2014 (AE2/RP2 rate: 50%/12%). A model was judged final if it significantly predicted AE2 or RP2 (p ≤ 0.05), was discriminative and well calibrated (AUC > 0.60; Hosmer-Lemeshow test p_HL > 0.05), which were assessed as the median over 1000 bootstrap samples.

RESULTS

Models for AE2 had superior discrimination to RP2 models (AUC = 0.63-0.65 vs. 0.51-0.65). The final AE2 model included mean esophageal dose and concurrent chemotherapy (AUC = 0.65; p < 0.0001). The final RP2 model was a slightly adjusted version of the RP2 model with the best discrimination, and included age, mean lung dose, and pulmonary comorbidity (AUC = 0.73; p < 0.0001).

CONCLUSION

Of the eight investigated and published NTCP models, one model successfully described AE2 and one slightly adjusted model successfully described RP2 in the independent cohort. Estimates from these two NTCP models will, therefore, be considered internally when prescribing patient-specific doses in LA-NSCLC patients.

C-reactive protein as a predictor of anastomotic leak in the first week after anterior resection for rectal cancer

AIM

Anastomotic leak (AL) after anterior resection results in increased morbidity, mortality and local recurrence. The aim of this study was to assess the ability of C-reactive protein (CRP) to predict AL in the first week after anterior resection for rectal cancer.

METHOD

A retrospective review of a prospectively maintained database that included all patients undergoing anterior resection between January 2008 and December 2013 was performed. The ability of CRP to predict AL was assessed using area under the receiver-operating characteristics (AUC) curves. The severity of AL was defined using the International Study Group of Rectal Cancer (ISREC) grading system.

RESULTS

Two-hundred and eleven patients were included in the study. Statistically significant differences in mean CRP values were found between those with and without an AL on postoperative days 5, 6 and 7. A CRP value of 132 mg/l on postoperative day 5 had an AUC of 0.75, corresponding to a sensitivity of 70%, a specificity of 76.6%, a positive predictive value of 16.3% and a negative predictive value of 97.5%. Multivariable analysis found that a CRP of > 132 mg/l on postoperative day 5 was the only statistically significant patient factor that was linked to an increased risk of AL (HR = 8.023, 95% CI: 1.936-33.238, P = 0.004).

CONCLUSION

Early detection of AL may minimize postoperative complications. CRP is a useful negative predictive test for the development of AL following anterior resection.

Liberal perioperative fluid administration is an independent risk factor for morbidity and is associated with longer hospital stay after rectal cancer surgery

INTRODUCTION Recent studies have advocated the use of perioperative fluid restriction in patients undergoing major abdominal surgery as part of an enhanced recovery protocol. Series reported to date include a heterogenous group of high- and low-risk procedures but few studies have focused on rectal cancer surgery alone. The aim of this study was to assess the effects of perioperative fluid volumes on outcomes in patients undergoing elective rectal cancer resection. METHODS A prospectively maintained database of patients with rectal cancer who underwent elective surgery over a 2-year period was reviewed. Total volume of fluid received intraoperatively was calculated, as well as blood products required in the perioperative period. The primary outcome was postoperative morbidity (Clavien-Dindo grade I-IV) and the secondary outcomes were length of stay and major morbidity (Clavien-Dindo grade III-IV). RESULTS Over a 2-year period (2012-2013), 120 patients underwent elective surgery with curative intent for rectal cancer. Median total intraoperative fluid volume received was 3680ml (range 1200-9670ml); 65/120 (54.1%) had any complications, with 20/120 (16.6%) classified as major (Clavien-Dindo grade III-IV). Intraoperative volume >3500ml was an independent risk factor for the development of postoperative all-cause morbidity (P=0.02) and was associated with major morbidity (P=0.09). Intraoperative fluid volumes also correlated with length of hospital stay (Pearson's correlation coefficient 0.33; P<0.01). CONCLUSIONS Intraoperative fluid infusion volumes in excess of 3500ml are associated with increased morbidity and length of stay in patients undergoing elective surgery for rectal cancer.

Endoscopic tattooing to aid tumour localisation in colon cancer: the need for standardisation

BACKGROUND/AIMS

An increasing number of colon and rectal tumours are being resected using laparoscopic techniques. Identifying these tumours intraoperatively can be difficult. The use of tattooing can facilitate an easier resection; however, the lack of standardised guidelines can potentially lead to errors intraoperatively and potentially result in worse outcomes for patients. The aim of this study was to identify the most reliable method of preoperative tumour localisation from the available literature to date.

METHODS

A literature review was undertaken to identify any articles related to endoscopic tattooing and tumour localisation during colorectal surgery.

RESULTS

To date there is still mixed evidence regarding tattooing techniques and the choice of ink that should be used. There are numerous studies demonstrating safe tattooing techniques and highlighting the risks and benefits of different types of ink available.

CONCLUSION

Based on the available studies we have recommended a standardised approach to endoscopic tattooing of colorectal tumours prior to laparoscopic resection.

High levels of X-linked Inhibitor-of-Apoptosis Protein (XIAP) are indicative of radio chemotherapy resistance in rectal cancer

BACKGROUND

The mainstay of treatment in rectal cancer is neoadjuvant radio chemotherapy prior to surgery, in an attempt to downstage the tumour, allowing for more complete removal during surgery. In 40 % of cases however, this neoadjuvant radio chemotherapy fails to achieve tumour regression, partly due insufficient apoptosis signaling. X-linked Inhibitor of Apoptosis Protein (XIAP) is an anti-apoptotic protein that has been reported to contribute to disease progression and chemotherapy resistance.

METHODS

We obtained rectal biopsy normal and matched tumour tissue from 29 rectal cancer patients with varying degrees of tumour regression, and using Western blot, examined anti-apoptotic XIAP and pro-apoptotic Smac protein levels in these tissues, with the aim to examine whether disturbed XIAP/Smac levels may be an indicator of neoadjuvant radio chemotherapy resistance. Expression of inhibitor of apoptosis proteins cIAP-1 and cIAP-2 was also examined.

RESULTS

We found that levels of XIAP increased in accordance with the degree of radio chemotherapy resistance of the tissue. Levels of this protein were also significantly higher in tumour tissue, compared to matched normal tissue in highly resistant tissue. In contrast, Smac protein levels did not increase with radio chemotherapy resistance, and the protein was similarly expressed in normal and tumour tissue, indicating a shift in the balance of these proteins. Post treatment surgical resection tissue was available for 8 patients. When we compared matched tissue pre- and post- radio chemotherapy we found that XIAP levels increased significantly during treatment in both normal and tumour tissue, while Smac levels did not change. cIAP-1 and cIAP-2 levels were not differentially expressed in varying degrees of radio chemotherapy resistance, and neoadjuvant therapy did not alter expression of these proteins.

CONCLUSION

These data indicate that disturbance of the XIAP/Smac balance may be a driver of radio chemotherapy resistance, and hence high levels of XIAP may be a useful indicator of neoadjuvant radio chemotherapy resistance in rectal cancer. Moreover, as XIAP levels increase with radio chemotherapy it is possible that a subset of more resistant tumour cells survive this treatment and may be resistant to further adjuvant treatment. Patients with resistant tumours highly expressing XIAP may benefit from alternative treatment strategies, such as Smac mimetics post neoadjuvant radio chemotherapy.