Dose Escalation Using Magnetic Resonance Guided High-Dose-Rate Endorectal Brachytherapy to Enhance Clinical Response after Neoadjuvant Radiotherapy in Rectal Adenocarcinoma

PURPOSE/OBJECTIVE(S)

To assess the proportion of patients with rectal adenocarcinoma achieving clinical complete response after neoadjuvant chemoradiation (NACTRT) and MR guided endorectal brachytherapy boost (MR-ERBT) MATERIALS/METHODS: Patients with rectal cancers (T2-T4/N0-N+) treated with concurrent chemoradiotherapy (50Gy/25# with Capecitabine) between June-2017 to April-2022. Post RT, patients having residual non-circumferential lesions <8cm in length were administered escalated-dose MR-ERBT with Ir192 HDR source. A median dose of 12Gy (8-15Gy) in 3 (2-3) fractions at 3-5 day intervals was delivered using MR-ERBT after external radiation. Data on near complete/complete clinical response (nCR/cCR) rates, local regrowth rates and clinical outcome were collected for analysis.

RESULTS

Of the 145 patients who received MR-ERBT, majority were staged as T3(78.7%) and N1-2 (77.5%) rectal cancers. Median tumor length was 4cm and 123 (85%) of the tumors were located in the lower rectum (0-5cm from anal verge). Seventy-six (52%) patients achieved cCR or nCR (37 cCR, 39 nCR) and were advised observation or watch and wait (WW) management. The 69 patients having partial response were advised surgery. The patients having nCR 16 (29%) underwent resection, of these 10 (62%) had pathological complete response (pCR). The patients with partial or poor response, 57 underwent resection and of these 11 (19%) had pCR, 12 patients refused surgery due to fear of permanent stoma and continued to be on follow up. Of the 79 patients undergoing resection, 36 (45.5%) had sphincter preserving surgeries. At the median follow up of 30 months, local regrowth was seen in 8 (10.5%) of patients on WW and 6 were surgically salvaged while other 2 had synchronous metastatic relapse. Thus, 56 (41%) achieved organ preservation and continued to be on WW management. Twelve (8,2%) patients developed distant metastasis in the entire cohort, 3 in the WW group and 9 in the resected group. There were no pelvic recurrences seen in the resected patients. The disease-free survival at 3 years were (96.1% vs 89% Observation vs. resected (p_0.05) respectively. The overall survival at 3 years were (93% vs 98% Observation vs. resected (p_0.44) respectively. Late rectal toxicity was observed in 16(11%) patients on observation CONCLUSION: Dose Escalated MR-EBRT is an effective and safe method to enhance complete clinical response, thus improving the rate of organ preservation for distal rectal cancers.

Computed Tomography-Based Interstitial Brachytherapy for Recurrent Cervical Carcinoma in the Vaginal Apex

AIMS

To determine the factors influencing the outcomes of patients with recurrences post-hysterectomy for cervical cancers treated with external beam radiotherapy (EBRT) and interstitial brachytherapy.

MATERIALS AND METHODS

This prospective study accrued 90 patients between October 2008 and May 2014. All patients had had a prior hysterectomy and were diagnosed with recurrent vaginal apex cancers with squamous cell carcinomas. All underwent EBRT of 50 Gy (2 Gy/fraction) using tomotherapy-based image-guided intensity-modulated radiotherapy with concurrent chemotherapy of weekly cisplatin (40 mg/m²) followed by high dose rate interstitial brachytherapy boost of 20 Gy (4 Gy/fraction twice a day). Local relapse, disease-free and overall survival were determined.

RESULTS

At a median follow-up of 74 months (4-123 months), 10/90 (11%) patients had local failure as the first site of relapse and 12/90 (13.3%) had first distant relapse. Only one patient had synchronous local and distant relapse. The 7-year local relapse-free, disease-free and overall survival were 87.6, 68.3 and 68.3%, respectively. Grade 2 and 3 rectal toxicity were seen in 5.6 and 3.1% of patients, respectively. Among these, two (2.2%) patients underwent temporary diversion colostomy due to vaginal sigmoid and rectovaginal fistula. Grade 2 and 3 bladder toxicity were seen in 5.6 and 1.1% of patients, respectively. In summary, the lateral disease extent (P = 0.048) and the presence of nodal disease at diagnosis (P = 0.08) had a statistically significant or borderline impact on local relapse without any impact on disease-free survival. Tumour size in itself did not affect overall survival.

CONCLUSION

With the integration of EBRT and interstitial brachytherapy, most vaginal apex recurrences can be salvaged. An excellent local control and survival is achievable using intensity-modulated radiotherapy with image guidance and concurrent chemotherapy followed by high dose rate interstitial brachytherapy.

Minimally invasive versus open pelvic exenterations for rectal cancer: a comparative analysis of perioperative and 3-year oncological outcomes

BACKGROUND

This study compared the surgical and oncological outcomes of open and minimally invasive pelvic exenteration.

METHODS

Patients who underwent pelvic exenterations for primary locally advanced rectal cancers with invasion of the urogenital organs (central and anterior disease) between August 2013 and September 2020 were reviewed retrospectively. Patients were categorized as undergoing open or minimally invasive surgery (MIS) and these groups were compared for perioperative outcomes and 3-year survival (overall, recurrence-free and local relapse-free survival). Multivariable Cox regression analysis was performed to assess the independent influence of approach of surgery and cancer features on recurrence-free survival (RFS).

RESULTS

Of the 158 patients who underwent pelvic exenteration, 97 (61.4 per cent) had open exenterations and 61 (38.6 per cent) patients had an MIS resection (44 patients (72 per cent) using laparoscopy and 17 (28 per cent) using robotic surgery). There were 96 (60.8 per cent) total pelvic exenterations and 62 (39.2 per cent) posterior pelvic exenterations. MIS exenterations had significantly longer operative times (MIS versus open: 640 mins versus 450 mins; P < 0.001) but reduced blood loss (MIS versus open: 900 ml versus 1600 ml; P < 0.001) and abdominal wound infections (MIS versus open: 8.2 versus 17.5 per cent; P = 0.020) without a difference in hospital stay (MIS versus open: 11 versus 12 days; P = 0.620). R0 resection rates and involvement of circumferential resection margins were similar (MIS versus open: 88.5 versus 91.8 per cent, P = 0.490 and 13.1 versus 8.2 per cent, P = 0.342 respectively). At a median follow-up of 29 months, there were no differences in 3-year overall survival (MIS versus open: 79.4 versus 60.2 per cent; P = 0.251), RFS (MIS versus open: 51.9 versus 47.8 per cent; P = 0.922) or local relapse-free survival (MIS versus open: 89.7 versus 75.2 per cent; P = 0.491. On multivariable analysis, approach to surgery had no bearing on RFS, and only known distant metastasis, aggressive histology and inadequate response to neoadjuvant radiation (pathological tumour regression grade greater than 3) predicted worse RFS.

CONCLUSION

MIS exenterations documented longer procedures but resulted in less blood loss and fewer wound infections compared with open surgeries. In the setting of an experienced centre, the hospital stay, R0 resection rates and oncological outcomes at 3 years were similar to those of open exenterations.

Can Post-Treatment MRI Features Predict Pathological Circumferential Resection Margin (pCRM) Involvement in Low Rectal Tumors

The MERCURY II study demonstrated the use of MRI-based risk factors such as extramural venous invasion (EMVI), tumor location, and circumferential resection margin (CRM) involvement to preoperatively predict pCRM (pathological CRM) outcomes for lower rectal tumors in a mixed group of upfront operated patients and patients who received neoadjuvant treatment. We aim to study the applicability of results of MERCURY II study in a homogeneous cohort of patients who received neoadjuvant chemoradiation (NACTRT) prior to surgery. After Institutional Review Board approval, post NACTRT restaging MRI of 132 patients operated for low rectal cancer between 2014 and 2018 were retrospectively reviewed by two radiologists for site of tumor, EMVI status, distance from anal verge (< 4 or > 4 cm), and mrCRM positivity. Findings were compared with post surgery pCRM outcomes using Fisher's exact test. Only 9/132(7%) patients showed pCRM involvement on histopathology, 8 of them being CRM positive on MRI (p = 0.01). The positive predictive value (PPV) of mrCRM positive status and pCRM status was 12.7% (95% CI: 9.7-16.5%), while the negative predictive value was 98.5% (95% CI: 91.4-99.8%) (p = 0.01). EMVI positive and anteriorly located tumors showed higher incidence of pCRM positivity but were not found to be significant (15% vs 5.2% and p = 0.13 and 8.6% vs 2.1% and p = 0.28, respectively). Unsafe mrCRM was the only factor significantly associated with pCRM positivity on post neoadjuvant restaging MRI. Tumors less than 4 cm from anal verge, anterior tumor location, and mrEMVI positivity did not show statistically significant results to predict pCRM involvement.

Outcomes of Definitive Treatment of Signet Ring Cell Carcinoma of the Rectum: Is Minimal Invasive Surgery Detrimental in Signet Ring Rectal Cancers?

The outcome of surgery for signet ring adenocarcinoma of rectum is suboptimal with high predilection for locoregional and peritoneal metastases. Lack of intercellular adhesion due to focal loss of epithelial cell adhesion molecule (EpCAM) may account for this. In such patients, whether minimal invasive surgery carries a high risk of dissemination by pneumoperitoneum and tumor implantation remains uncertain. The aim of this study was to compare the outcomes of patients undergoing minimally invasive surgery (MIS) versus open surgery in patients with signet ring cell adenocarcinoma of rectum. A retrospective study was conducted at a tertiary care center over 3 years on 39 patients undergoing open surgery and 40 patients undergoing MIS diagnosed with signet ring cell carcinoma (SRCC) identified from our surgical database. Patient characteristics in terms of demographics, clinicoradiological staging, neoadjuvant therapy, and type of surgery with morbidity were compared in the two groups. Data on patients undergoing adjuvant therapy and 3 years disease-free survival (DFS) and overall survival (OS) were analyzed. Recurrence patterns in both groups were separately identified as locoregional, peritoneal, or systemic. The number of patients undergoing surgery in the two arms was 40 (MIS) and 39 (open). In the MIS arm, mean DFS was 29 months whereas in the open arm, it was 25.8 months. The mean OS was 33.65 months for the MIS arm and that for the open arm was 36.34 months. This retrospective study reveals no significant difference in outcomes of surgery for signet ring cell rectal cancers with either MIS or open approach.

Early Detection for Colorectal Cancer: ASCO Resource-Stratified Guideline

PURPOSE

To provide resource-stratified, evidence-based recommendations on the early detection of colorectal cancer in four tiers to clinicians, patients, and caregivers.

METHODS

American Society of Clinical Oncology convened a multidisciplinary, multinational panel of medical oncology, surgical oncology, surgery, gastroenterology, health technology assessment, cancer epidemiology, pathology, radiology, radiation oncology, and patient advocacy experts. The Expert Panel reviewed existing guidelines and conducted a modified ADAPTE process and a formal consensus-based process with additional experts (Consensus Ratings Group) for two round(s) of formal ratings.

RESULTS

Existing sets of guidelines from eight guideline developers were identified and reviewed; adapted recommendations form the evidence base. These guidelines, along with cost-effectiveness analyses, provided evidence to inform the formal consensus process, which resulted in agreement of 75% or more.

CONCLUSION

In nonmaximal settings, for people who are asymptomatic, are ages 50 to 75 years, have no family history of colorectal cancer, are at average risk, and are in settings with high incidences of colorectal cancer, the following screening options are recommended: guaiac fecal occult blood test and fecal immunochemical testing (basic), flexible sigmoidoscopy (add option in limited), and colonoscopy (add option in enhanced). Optimal reflex testing strategy for persons with positive screens is as follows: endoscopy; if not available, barium enema (basic or limited). Management of polyps in enhanced is as follows: colonoscopy, polypectomy; if not suitable, then surgical resection. For workup and diagnosis of people with symptoms, physical exam with digital rectal examination, double contrast barium enema (only in basic and limited); colonoscopy; flexible sigmoidoscopy with biopsy (if contraindication to latter) or computed tomography colonography if contraindications to two endoscopies (enhanced only).

Treatment of Patients With Early-Stage Colorectal Cancer: ASCO Resource-Stratified Guideline

PURPOSE

To provide resource-stratified, evidence-based recommendations on the treatment and follow-up of patients with early-stage colorectal cancer.

METHODS

ASCO convened a multidisciplinary, multinational Expert Panel that reviewed existing guidelines and conducted a modified ADAPTE process and a formal consensus process with additional experts for one round of formal ratings.

RESULTS

Existing sets of guidelines from 12 guideline developers were identified and reviewed; adapted recommendations from six guidelines form the evidence base and provide evidence to inform the formal consensus process, which resulted in agreement of 75% or more on all recommendations.

RECOMMENDATIONS

For nonmaximal settings, the recommended treatments for colon cancer stages nonobstructing, I-IIA: in basic and limited, open resection; in enhanced, adequately trained surgeons and laparoscopic or minimally invasive surgery, unless contraindicated. Treatments for IIB-IIC: in basic and limited, open en bloc resection following standard oncologic principles, if not possible, transfer to higher-level facility; in emergency, limit to life-saving procedures; in enhanced, laparoscopic en bloc resection, if not possible, then open. Treatments for obstructing, IIB-IIC: in basic, resection and/or diversion; in limited or enhanced, emergency surgical resection. Treatment for IIB-IIC with left-sided: in enhanced, may place colonic stent. Treatment for T4N0/T3N0 high-risk features or stage II high-risk obstructing: in enhanced, may offer adjuvant chemotherapy. Treatment for rectal cancer cT1N0 and cT2n0: in basic, limited, or enhanced, total mesorectal excision principles. Treatment for cT3n0: in basic and limited, total mesorectal excision, if not, diversion. Treatment for high-risk patients who did not receive neoadjuvant chemotherapy: in basic, limited, or enhanced, may offer adjuvant therapy. Treatment for resectable cT3N0 rectal cancer: in enhanced, base neoadjuvant chemotherapy on preoperative factors. For post-treatment surveillance, a combination of medical history, physical examination, carcinoembryonic antigen testing, imaging, and endoscopy is performed. Frequency depends on setting. Maximal setting recommendations are in the guideline. Additional information can be found at www.asco.org/resource-stratified-guidelines.

NOTICE

It is the view of the American Society of Clinical Oncology that health care providers and health care system decision makers should be guided by the recommendations for the highest stratum of resources available. The guidelines are intended to complement but not replace local guidelines.

Persistent involvement of anterior mesorectal fascia in carcinoma rectum - extended resection of rectum vs total pelvic exenteration: results from a single-centre retrospective study

AIM

Involvement of the anterior mesorectal fascia (iAMRF) after neoadjuvant treatment leads to either resection of the involved organ alone [extended resection of the rectum (ERR)] or total pelvic exenteration (TPE). The purpose of this study was to compare the rate of recurrence and survival of patients undergoing ERR or TPE for iAMRF after neoadjuvant treatment. The outcome of patients who underwent total mesorectal excision after downstaging was also compared.

METHOD

This was a retrospective study of primary rectal cancer patients.

RESULTS

Of 237 patients, 61 (21.5%) patients with nonmetastatic carcinoma rectum had iAMRF at baseline. Ten patients defaulted before completion of neoadjuvant chemoradiotherapy. After neoadjuvant chemoradiotherapy, 22 patients (43.1%) developed systemic metastases, seven patients (13.8%) were downstaged to free anterior mesorectal fascia and underwent total mesorectal excision (anterior resection/abdominoperineal resection) and the remaining 22 patients (43.1%) had persistent iAMRF. Thirteen patients with persistent iAMRF underwent ERR, whereas nine patients underwent TPE. The median duration of hospital stay in the TPE group was 13 days (10-26), whereas it was 7 days (5-21) in the ERR group. A clear circumferential resection margin, R0 resection, was achieved in all patients with TPE and ERR. After a median follow-up of 31.6 months, five patients with TPE (55.6%), four patients with ERR (30.7%) and three patients in the downstaged group (42.9%) developed systemic recurrence. None of the patients with TPE and the downstaged group developed local recurrence, whereas three patients with ERR (23.1%) developed local recurrence. Median disease-free survival was 12.3 months in the TPE group, 18.9 months in the ERR group and 10.6 months in the downstaged group, whereas mean overall survival was 36.2, 32.8 and 27.9 months, respectively.

CONCLUSION

Although there is no significant difference in the overall survival and disease-free survival, ERR is associated with a high risk of local recurrence compared to TPE and the downstaged group.

Clinical Utility of Staging Laparoscopy for Advanced Obstructing Rectal Adenocarcinoma: Emerging Tool

The multimodal treatment for advanced rectal adenocarcinoma mandates accurate preoperative staging with contrast-enhanced computed tomography (CECT) of the thorax, abdomen, and pelvis, and magnetic resonance imaging (MRI) of the pelvis. Unlike gastric cancer, the role of staging laparoscopy (SL) in advanced colorectal cancer has not been evaluated. This study aims to evaluate the clinical value of SL in treatment decision-making for advanced rectal cancer (RC) with near or complete obstructing tumors. Observational review of colorectal database at Tata Memorial Hospital from January 2013 to December 2016 identified 562 patients diagnosed and treated for advanced RC. Of the 562 cases, 48.7% (274) were clinically and radiologically diagnosed of near or complete obstructing advanced RC. Medical records of 34% (94/274) who underwent SL with diversion stoma (DS) were analyzed. In the absence of ascites, extensive peritoneal deposits, and unresectable liver metastases on SL, a curative treatment was offered, which entailed neoadjuvant chemoradiation (NACTRT), whereas the cohort of patients with extensive peritoneal disease received palliative therapy. Of the 94 patients with advanced RC, conventional imaging studies staged 73.5% (69/94) cohort as non-metastatic locally advanced and 26.5% (25/94) had potentially resectable metastatic RC. Pre-therapeutic SL upstaged the disease by 26% (18/69) and 8% (2/25) in locally advanced and potentially resectable metastatic RC cohorts, respectively. Treatment decision changed in 21.2% (20/94) of the patients, and midline laparotomy was thus avoided. In our observational study, SL was found to be a safe and effective staging modality in RC; it detected occult peritoneal disease and prevented midline laparotomy in 21.2% of the cohort, which was of value to determine treatment strategy in patients with advanced RC before initiating NACTRT. SL and laparoscopic-assisted de-functioning stoma were associated with minimal morbidity and led to early initiation of NACTRT.

Carcinoembryonic antigen directed PET-CECT scanning for postoperative surveillance of colorectal cancer

AIM

During the follow-up of surgically resected colorectal cancer (CRC), positron emission tomography-contrast-enhanced computed tomography (PET-CECT) is indicated for asymptomatic elevation of carcinoembryonic antigen (CEA) > 5 ng/ml and no obvious site of recurrence on clinical examination and basic imaging. As an institutional policy, a PET-CECT scan was performed at our institute whenever (1) CEA levels rose above 5 ng/ml and (2) CEA values were doubled (even if the CEA level was < 5 ng/ml). Our aim was to correlate the range of CEA elevation with recurrence rates and to evaluate the diagnostic utility of PET-CECT scanning in this setting.

METHOD

We retrospectively analysed all cases where a PET-CECT scan was performed for elevated CEA levels during surveillance visits after complete resection of the primary tumour followed by adjuvant therapy. This study was conducted from 1 January 2013 to 31 July 2015.

RESULTS

In all, 104 patients underwent a PET-CECT scan for rising CEA values, and 62 patients (59.6%) were found to have recurrent disease. At CEA levels < 5, 5.1-10, 10.1-15, 15.1-50 and > 50 ng/ml, disease recurred in 10%, 45%, 70%, 94% and 100% patients, respectively. Sensitivity, specificity, positive predictive value and negative predictive value of the PET-CECT scan were 92.7%, 95.2%, 96.2% and 90.9%, respectively. Elevation of CEA levels during follow-up was indicative of recurrence in 68% of the secretors and 45% of the non-secretors (based on baseline CEA status).

CONCLUSION

In the setting of rising CEA levels during follow-up of patients with CRC, a PET-CECT scan is a valuable tool to detect recurrence, irrespective of the baseline CEA secretor status. The likelihood of recurrence of disease was directly proportional to the value of the raised CEA level.

High nodal positivity rates even in good clinical responders after chemoradiation of rectal cancer: is organ preservation feasible?

AIM

Local excision (LE) is emerging as a treatment option for rectal cancer responding well to chemoradiation. However, it does not address the mesorectal nodal burden. We aimed to identify the factors influencing nodal positivity and subsequently defined a low-risk group by including only patients at low risk.

METHOD

A single-centre, retrospective database analysis was carried out of patients with radically resected rectal cancer after neoadjuvant chemoradiation.

RESULTS

This study included 524 patients with predominantly low rectal tumours. Nodal positivity among ypT0, T1 and T2 groups was 14.7%, 28% and 30%, respectively. Multivariate analysis with stepwise logistic regression identified the following low-risk features: age ≥ 40 years, nonsignet ring cell carcinoma (SRCC) histology and pathological complete response (pCR). Sixty-nine patients fulfilling all three criteria were analysed and the nodal positivity was found to be 10.1%, which implies that, if these patients had been selected for LE, one in 10 would have had positive mesorectal nodes.

CONCLUSION

Even in patients with low-risk criteria (pCR, non-SRCC histology and age ≥ 40 years), the residual positive nodal disease burden is 10%. Whether this high incidence of residual nodal disease translates into a similar risk of locoregional recurrence if an organ-preservation strategy is adopted is unclear.

An Improved Technique for the Determination of Isocyanurate and Isocyanate Conversion by Photoacoustic FTIR

Conventional rigid polyisocyanurate (PUIR) foams blown with HCFC-141b often suffer from poorer compressive strengths, dimensional stability and inferior flammability properties when compared to foams blown with CFC-11. It is often hypothesized that these properties can be improved by increasing the isocyanurate (or "trimer") conversion by means of catalyst optimization and increased isocyanate index. A convenient, yet reliable method for the determination of the amount of isocyanurate in a PUIR foam has been missing in this industry for a long time, though several attempts have been documented in the literature. The purpose of this paper is to introduce an improved isocyanurate conversion test by photoacoustic Fourier Transform Infra Red (FTIR) technique. This involves creating a baseline through three anchor points at approximately 1637 cm−1, 1469 cm−1, and 1349 cm−1. The absorbance of the isocyanurate peak at 1410 cm−1 is taken relative to the absorbance of the phenyl peak at 1602 cm−1. The phenyl peak is preferred to the urethane peak because the absorbance of phenyl groups in a foam is inherent to the amounts of polyols and isocyanates used in the foaming reaction, whereas the urethane linkages in the foam are created by a reaction between the two and are, therefore, variable depending on the extent of the reaction in the presence of catalysts and possibly water. In addition, the relative ratios of the absorbances of isocyanate end groups (at 2277 cm−1) and carbodiimide groups (at 2136 cm−1) to the phenyl groups can also be determined by generating a baseline through the anchor points at approximately 2470 cm−1, 2207 cm−1 and 2000 cm−1. This allows one to gain a better assessment of the overall kinetics of the isocyanate reactions and creates opportunities to improve the isocyanurate conversion through formulation optimization. The method is not limited to polyisocyanurate foams, as isocyanate conversion is an important parameter to follow in polyurethane foams as well, especially in all carbon dioxide blown foams. The method was found to be quite reproducible, and further statistical analysis to ensure the validity of this technique is under way.

Multidisciplinary management of colorectal adenocarcinoma associated with anal fistula: an Indian series

AIM

Adenocarcinomas associated with anal fistula are rare and often present at an advanced stage. They are often mistaken for commonly occurring benign diseases, leading to delayed diagnosis. Previous reports have predicted inferior oncological outcomes for these cases compared with sporadic rectal cancers. We are presenting our series of patients with colorectal adenocarcinoma associated with anal fistula who were treated with multimodality therapy at a tertiary cancer centre in India.

METHOD

This was a retrospective review of a prospectively maintained database of patients treated at our centre between 1 July 2013 and 31 March 2015. Of the 15 patients included in the study, 11 had prior intervention in the form of seton placement or fistulotomy. Fourteen patients had circumferential resection margin (CRM) involvement at initial workup and hence were given neoadjuvant chemoradiotherapy (NACRT). None of the patients had distant metastasis and only 15% had regional nodal involvement.

RESULTS

All 13 patients included in the final analysis underwent abdominoperineal excision (APE). Ten patients (73%) underwent extralevator APE. Plastic reconstruction in the form of a V-Y advancement flap for perineal closure was required in six patients (46%). On histopathological examination, a mucinous component was found to be present in 11 patients (73%). The quality of total mesorectal excision was complete in 92% patients. The CRM was free in 92% of patients. Median overall survival and disease-free survival were not reached.

CONCLUSION

Colorectal adenocarcinomas associated with fistula are locally aggressive malignancies with a low incidence of lymph node involvement and distant metastasis. NACRT, wider resection in the form of extralevator APE, and liberal use of plastic reconstruction may result in favourable outcomes.

Vaginal displacement during course of adjuvant radiation for cervical cancer: results from a prospective IG-IMRT study

OBJECTIVE

To compare internal target volume (ITV) generated using population-based displacements (ITV_study) with empty and full bladder scan fusion (ITV_EBFB) for organ-at-risk (OAR) doses during adjuvant intensity-modulated radiation therapy (IMRT) for cervical cancer.

METHODS

From January 2011 to October 2012, patients undergoing IMRT were included. CT simulation was carried out after inserting vault markers. Planning target volume (PTV)_EBFB received 50 Gy per 25 fractions. Pre-treatment megavoltage CT (MVCT) was performed. MVCTs were registered using bony landmarks with Day 1 MVCT. Displacement of the centre of mass of markers was measured along each axis. Directional ITV was calculated using mean ± 2 standard deviations (SDs) (ITV_study). Replanning was performed using PTV study, and OAR doses were compared with PTV_EBFB using Wilcoxon test.

RESULTS

A total of 348/386 data sets were evaluable for 16 patients. The median vaginal displacement was 1.2 mm (SD, 1.3 mm), 4.0 mm (SD, 3.5 mm) and 2.8 mm (SD, 3.3 mm) in the mediolateral, superoinferior and anteroposterior directions, respectively. The ITV margins were 4.1, 10.3 and 10.6 mm. ITV_study and ITV_EBFB were 115.2 cm(3) (87.7-152.2 cm(3)) and 151 cm(3) (95.7-277.1 cm(3)) (p < 0.0001), respectively. PTV_study and PTV_EBFB were 814 and 881 cm(3) (p < 0.0001), respectively. Median doses to the bladder were lower with the PTV_study (46.2 Gy vs 43.2 Gy; p = 0.0001), and a similar trend was observed in the volume of the small bowel receiving 40 Gy (68.2 vs 60.1 cm(3); p = 0.09).

CONCLUSION

Population-based PTV margins can lead to reduction in OAR doses.

ADVANCES IN KNOWLEDGE

Population-based ITV may reduce OAR doses while executing adjuvant IMRT for cervical cancer.

Evaluation of internal target volume in patients undergoing image-guided intensity modulated adjuvant radiation for gastric cancers

OBJECTIVE

To evaluate three-dimensional (3D) displacements of gastric remnant during adjuvant radiation.

METHODS

From January 2011 to September 2012, patients undergoing adjuvant image-guided intensity-modulated radiation on tomotherapy were included. Megavoltage CT (MVCT) data sets from daily treatment were coregistered with Day 1 MVCT. Residual stomach remnant was delineated on the data set, while the remaining were blinded to previous day contours. Gastric volume and centre of mass (COM) were determined for all data sets. The 3D deviation of COM was calculated for each fraction. Mean 3D and standard deviation (SD) were calculated for each patient and study population, and a 95% confidence interval (CI) was determined. Also, systematic and random errors for patient population and internal target volume (ITV) margin were calculated using the van Herk formula.

RESULTS

There were 119 images available for 15 patients. Mean volume of remnant was 319 cm(3) (146-454 cm(3)). Gastric remnant expanded in different directions with no specific directional expansion. Average deviations in mediolateral, superoinferior and anteroposterior directions were 9 mm (3-25 mm; SD, 5 mm), 6 mm (3-16 mm; SD, 4 mm) and 5 mm (1-10 mm; SD, 3 mm), respectively, with 95% CI of 18, 15 and 11 mm, and ITV margins of 19.2, 13.5 and 7.8 mm, respectively.

CONCLUSION

There is large variation in gastric remnant volume during the course of radiation. Large displacements observed in the present study necessitate the need to investigate adaptive techniques for optimizing intensity-modulated radiotherapy (IMRT) delivery.

ADVANCES IN KNOWLEDGE

An adaptive strategy needs to be developed to optimize IMRT delivery for adjuvant gastric irradiation.