Gynecologic brachytherapy-II: Intravaginal brachytherapy for carcinoma of the endometrium

Adjuvant vaginal brachytherapy alone for high risk localized endometrial cancer as defined by the three major randomized trials of adjuvant pelvic radiation

OBJECTIVE

Controversy exists regarding optimal management of high risk localized endometrial cancer. Given that vaginal brachytherapy (VB) alone is used routinely at our institution, we retrospectively reviewed our outcomes among high risk patients defined according to the PORTEC, GOG 99, and/or Aalders randomized trials of pelvic radiation versus observation to determine if acceptable rates of locoregional control could be achieved with vaginal brachytherapy alone in this highest risk patient population.

METHODS

The Roswell Park Cancer Institute hospital tumor registry was used to identify all patients with Stage I or IIA endometrial cancer treated between January 1992 and June 2006. A total of 464 patients were identified. Of 261 patients who received post-operative RT, 225 received VB alone. Of those 225, 87 met the high risk criteria as designated by PORTEC (at least 2 of the following high risk features: age>60, Grade 3, and/or myometrial invasion >or=Occurrences of the mathematical operator' (='were changed to 'OE'. Please check.-->50%), GOG 99 (any age with 3 high risk features: Grade 2-3, >66% myometrial invasion, and/or LVSI; age >or=50 with 2 high risk features; or age >or=70 with 1 high risk feature), and/or Aalders (Stage IC, Grade 3). Descriptive recurrence statistics are provided.

RESULTS

Among 87 high risk patients treated with VB alone, 36, 77, and 14 were high risk per PORTEC, GOG 99, and Aalders respectively. Forty (46%) underwent pelvic lymph node dissection. With a median follow-up of 52 months, 3 (3.4%) pelvic recurrences were observed including 1 vaginal recurrence, 1 pelvic recurrence, and 1 local recurrence involving both the vagina and pelvis. All 3 local recurrences were successfully salvaged with pelvic RT+/-surgery.

CONCLUSIONS

This represents one of the largest known series of high risk localized endometrial cancer treated with VB alone. The observed 3.4% locoregional recurrence compares favorably with the 5% locoregional recurrence noted among the highest risk patients receiving pelvic RT in the PORTEC, GOG 99, and Aalders randomized trials. In this single institution experience, the 3 local recurrences were salvaged. Based on these findings, we will continue to use VB alone in the adjuvant setting for patients with high risk localized endometrial cancer.

Prospective clinical trial of bladder filling and three-dimensional dosimetry in high-dose-rate vaginal cuff brachytherapy

PURPOSE

To investigate the effect of bladder filling on dosimetry and to determine the best bladder dosimetric parameter for vaginal cuff brachytherapy.

METHODS AND MATERIALS

In this prospective clinical trial, a total of 20 women underwent vaginal cylinder high-dose-rate brachytherapy. The bladder was full for Fraction 2 and empty for Fraction 3. Dose-volume histogram and dose-surface histogram values were generated for the bladder, rectum, and urethra. The midline maximal bladder point (MBP) and the midline maximal rectal point were recorded. Paired t tests, Pearson correlations, and regression analyses were performed.

RESULTS

The volume and surface area of the irradiated bladder were significantly smaller when the bladder was empty than when full. Of the several dose-volume histogram and dose-surface histogram parameters evaluated, the bladder maximal dose received by 2 cm(3) of tissue, volume of bladder receiving >/=50% of the dose, volume of bladder receiving >/=70% of the dose, and surface area of bladder receiving >/=50% of the dose significantly predicted for the difference between the empty vs. full filling state. The volume of bladder receiving >/=70% of the dose and the maximal dose received by 2 cm(3) of tissue correlated significantly with the MBP. Bladder filling did not alter the volume or surface area of the rectum irradiated. However, an empty bladder did result in the nearest point of bowel being significantly closer to the vaginal cylinder than when the bladder was full.

CONCLUSIONS

Patients undergoing vaginal cuff brachytherapy treated with an empty bladder have a lower bladder dose than those treated with a full bladder. The MBP correlated well with the volumetric assessments of bladder dose and provided a noninvasive method for reporting the MBP dose using three-dimensional imaging. The MBP can therefore be used as a surrogate for complex dosimetry in the clinic.

Radiotherapy of endometrial carcinoma: Who needs to be irradiated?

Due to gynecological oncology general strategy and everyday aspiration for individual approach to malignant tumors, guidelines in treatment approach are not finally established, and they are controversial in some demands with age of the patients. If we look general treatment strategy approach to invasive endometrial cancer it is proved that operative treatment is priority and base line of treating endometrial carcinoma I and II clinical stage (FIGO) if there is general conditions for surgery, allowing complicated treatment in this age. Previous experience are showing that decision about application of therapy procedures in treatment of endometrial carcinoma every case have to has individual approach, regarding all known prognostic criteria: clinical stage, histological type, myometrial infiltration, lymph-vascular space involvement, size of the tumor and its localiza?tion, depth of myometrial infiltration, invading of serosa, cervix and adnexa, present of hormonal tissue receptors, information about lymph node: number, size and size of the biggest metastases, data about both extra nodular expansion of tumor and peritoneal cytology. The use of postoperative radiotherapy should be limited to group of patients with highly enough risk of locoregional recurrence (15% and more) as risk warranty of morbidity connected to radiological treatment. Therefore, the goal of postoperative radiotherapy appliance is to achieve maximum locoregional disease control and survival without relapse. New Radiotherapy (RT) techniques, Conformal Radiotherapy (CFRT) and Intensity Modulated radiotherapy (IMRT), reduce the risk of complications, especially for patients with multimodal treatment.

Predictors of vaginal relapse in stage I endometrial cancer

OBJECTIVE

To identify factors predictive of vaginal relapse in stage I endometrial cancer, thereby potentially facilitating the selection of patients who may benefit from vaginal brachytherapy.

METHODS

The study population included 632 patients with stage I endometrial cancer managed with hysterectomy at our institution between 1984 and 1996. Median follow-up was 73 months; 122 patients (19%) received adjuvant radiotherapy.

RESULTS

Overall, 2.9% of the stage I cohort developed vaginal relapse at 5 years. Vaginal relapse was observed in 1.7% of patients who received radiotherapy and in 3.0% of those whose treatment did not include radiotherapy (P = 0.36). Cox regression analysis (including radiotherapy) identified only grade 3 differentiation (hazard ratio = 3.83, P = 0.007) as an independent predictor of vaginal relapse. Patients with a low-grade tumor had a 5-year vaginal relapse rate of 2%, compared with 7% for those with a grade 3 tumor. When only patients who did not receive adjuvant radiotherapy were considered, both grade 3 tumor and lymphovascular invasion were significant predictors of vaginal relapse (P < 0.05). When neither variable was present, 2% of patients experienced vaginal relapse at 5 years, compared with 11% when either 1 was present (P < 0.001). Depth of myometrial invasion was not a significant predictor of vaginal recurrence.

CONCLUSION

Histologic grade 3 tumor and lymphovascular invasion were the cogent predictors of vaginal relapse in our population. The cost and morbidity of vaginal brachytherapy should be balanced against the potential risk of vaginal relapse in this group of patients.

Clinical effects in a cohort of cancer patients overexposed during external beam pelvic radiotherapy

PURPOSE

To evaluate the clinical outcome of 28 overexposed cancer patients in a cohort of 153 treated with pelvic irradiation and to correlate the outcome with the doses received.

METHODS AND MATERIALS

Between August 2000 and March 2001, 153 patients were treated at the Instituto Oncológico Nacional of Panama with radiotherapy for cancers of the cervix, uterus, endometrium, prostate, and rectum using conventional techniques. In 56 patients, irradiated with partially blocked teletherapy fields, the treatment times were determined using a treatment planning system that generated isodose distributions. The absorbed doses received by the patients were calculated and the biologically effective doses (BEDs) and 2-Gy equivalent doses derived. The clinical outcome was evaluated using the Radiation Therapy Oncology Group (RTOG) and late effects on normal tissues-subjective, objective, management, analytic scales (LENT/SOMA). The relationships between clinical outcome and dose were investigated and compared with published data.

RESULTS

Of the 56 patients for whom treatment times were generated with the treatment planning system, 28 received some doses per fraction approximately double those prescribed. Using an alpha/beta = 10 Gy, the tumor BED(10) values ranged from 77 to 225 Gy. The rest of the patients received doses within 10% of the prescribed values. Seventeen of the 28 overexposed patients died 35 days to 21 months after treatment; 13 of the fatalities were caused by rectal complications. Survival was longer in those patients who had undergone colostomy. Bladder complications were less enhanced. The nonoverexposed patients with cervical cancer exhibited a greater incidence of treatment failures than generally reported in other centers.

CONCLUSION

This study provides the clinical outcome after high doses of pelvic radiotherapy in a range not previously well documented. For cervical cancer patients receiving both tele- and brachytherapy, some deaths in this overexposure cohort occurred from assumed consequential rectal injury within 2 years, when the BED(10) values exceeded 70-80 Gy. The incidence was asymptotic to 100% fatalities at >150 Gy. This confirmed and extended other data in the literature.

Geometric and dosimetric variations of ICRU bladder and rectum reference points in vaginal cuff brachytherapy using ovoids

PURPOSE

To investigate the interfractional geometric and dose variations of rectal reference point (R) and bladder reference point (BL) doses in patients receiving vaginal cuff irradiation using high-dose-rate brachytherapy with 2 ovoids and the change in calculated radiobiologic-equivalent dose of R and BL.

METHODS

ICRU-38 R and BL reference doses were calculated. The variation in positions of ovoids, R, and BL were determined. Whether the magnitude of displacement shows a time trend and has an effect on calculated R and BL doses was evaluated. The relation between the ovoid diameter and both the magnitude of displacement and changes in R and BL doses was studied. Changes in radiobiologic-equivalent dose of rectum and bladder were determined.

RESULTS

The average magnitude of displacements was 3.2 and 12.1 mm, showed no time trend, and no tendency to displacement in a certain direction. Mean changes in BL and R doses were 64-75 cGy and 47-58 cGy, respectively. There was a relation between neither ovoid size and displacement nor R and BL dose change. Dose and geometric variation showed no correlation (p > 0.05). The differences in radiobiologic-equivalent dose of R and B were not significant.

CONCLUSION

Although there were significant differences in R and B position and doses among the fractions, the magnitudes of dose changes were relatively small, and total calculated radiobiologic-equivalent doses of R and B did not change significantly. According to the results of this study, the benefit of treatment planning is limited to supporting treatment planning in each fraction.

Multi-channel intracavitary vaginal brachytherapy using three-dimensional optimization of source geometry

BACKGROUND AND PURPOSE

A new multi-channel vaginal cylinder has been constructed. The dose distribution is compared to that of a central channel cylinder.

PATIENTS AND METHODS

The source channels of the multi-channel cylinder are placed close to the treatment volume, which means that the dose gradient in the radial direction is steep. Therefore the dose is enhanced close to the cylinder surface and lowered at larger distances as compared to the central channel cylinder. Three patients were each CT-scanned twice with a vaginal cylinder in situ. CT-based 3D dose-planning studies were used to calculate the dose distribution. Dose-volume histograms (DVHs) were generated for rectum and bladder, and a quantification of high dose volumes was calculated from the DVHs. Dose to the vaginal mucosa was calculated.

RESULTS

The dose to the critical organs depends on the depth of normalization. When the dose is normalized on the cylinder surface the hot spot dose to bladder and rectum is reduced by 16 and 17%, respectively, whereas mucosal dose remains the same. When the dose is normalized at 5 mm depth the hot spot dose to bladder and rectum is reduced by 1 and 3%, respectively, whereas mucosal dose is enhanced by 17%.

CONCLUSIONS

The multi-channel cylinder makes it possible to spare the rectum and the bladder at the expense of enhanced mucosal dose.

High-risk surgical stage 1 endometrial cancer: outcomes with vault brachytherapy alone

OBJECTIVE

Prior to 1995, in our center, patients with surgically staged endometrial cancer with greater than 50% myoinvasion (FIGO 1C) were treated with vault brachytherapy and whole pelvis (WP) radiotherapy despite negative nodes. After October 1, 1995, these patients were treated with vault brachytherapy alone. The aim of this study was to ensure that the survival and recurrence rate had not changed.

METHODS

A retrospective review of Cancer Care Manitoba charts was undertaken. All patients diagnosed with endometrioid adenocarcinoma between October 1, 1995, and March 1, 2001, were reviewed. Data for all FIGO surgical stage 1 patients, and a subset of stage 1C patients, were analyzed and compared with those of a historical control group, composed of patient data previously collected in our center (1978 to 1990) [Gynecol. Oncol. 55 (1994), 51].

RESULTS

A total of 172 patients had negative selective pelvic lymphadenectomy and FIGO stage 1 disease. Fifty-three stage 1C patients were spared WP radiotherapy. Median follow-up was 32 months. Recurrence rate in FIGO stage 1 disease was 2.3% (4/172) and for the subset 1C was 5.7% (3/53). The recurrence rate was not statistically significantly different from that of the historical control group, 3.6% for stage 1 (P = 0.562) and 7.2% for stage 1C (P = 0.51). Two- and five-year survival rates for stage 1 patients in this study were 97 and 95%, respectively. In the historical group, 2- and 5-year survival rates were 97 and 94%.

CONCLUSION

Whole pelvis radiotherapy can be safely omitted in patients with FIGO stage 1C endometrial cancer if nodal status is known.