Clinical and dosimetric consequences of imperfect applicator insertion in cervical cancer brachytherapy.

PURPOSE: This study analyzes clinical consequences and dosimetric variations after imperfect brachytherapy insertions. It examines treatment decisions after such insertions in patients having difficult anatomy, which leads to good subsequent insertions with acceptable dose volume parameters. MATERIAL AND METHODS: We reviewed images of all insertions performed during last one year and sorted faulty ones out. Clinical outcome was assessed, analyzing original treatment records. Repeat three-dimensional planning using identical dose-optimization-technique compared their dosimetry. Statistical analysis using SPSS®-Statistics-software included Fisher's-exact-test to analyze predisposing factors for faulty insertions and predictive factors for subsequent satisfactory insertion. Friedman test was used to compare dose-volume-effects of normalization. RESULTS: Eighteen of 292 brachytherapy plans revealed imperfect insertions, including thirteen perforations (4.5%). Lack of pre-planning, obstructing mass, narrow vagina, acute anteversion of uterus, and multi-parity were significant (p ≤ 0.05) predisposing factors for atypical insertions. Satisfactory optimization was possible after correcting acute anteflexion or positioning tandem in retroverted direction in uncorrectable retroverted uterus. Dose normalization at point A shifted optimized dose from contoured volume to point of normalization, often undesirably. This difference, however, was statistically not significant (p = 0.121). In patients having obstructing mass, subsequent insertions were perfect, and dose volume parameters were acceptable only when full prescribed dose was delivered to at least 60% volume of the mass after a faulty insertion (p < 0.001). CONCLUSIONS: Pre-planning by imaging is suggested in all cases of brachytherapy. Insertion of adequate length of tandem aligned to uterine axis is warranted for adequate tumor coverage. Whenever detected, acute anteflexion and mobile retroversion should be corrected. Tandem inserted in retroverted direction in uncorrectable retroverted uterus generates acceptable dose volume parameters. In cases with obstructive cervical mass, good subsequent insertion is possible with acceptable dose volume parameters, if planned dose can be delivered to its 60% volume.

Comparison of dose volume parameters evaluated using three forward planning - optimization techniques in cervical cancer brachytherapy involving two applicators.

PURPOSE: This study is intended to compare dose-volume parameters evaluated using different forward planning- optimization techniques, involving two applicator systems in intracavitary brachytherapy for cervical cancer. It looks for the best applicator-optimization combination to fulfill recommended dose-volume objectives in different high-dose-rate (HDR) fractionation schedules. MATERIAL AND METHODS: We used tandem-ring and Fletcher-style tandem-ovoid applicator in same patients in two fractions of brachytherapy. Six plans were generated for each patient utilizing 3 forward optimization techniques for each applicator used: equal dwell weight/times ('no optimization'), 'manual dwell weight/times', and 'graphical'. Plans were normalized to left point A and dose of 8 Gy was prescribed. Dose volume and dose point parameters were compared. RESULTS: Without graphical optimization, maximum width and thickness of volume enclosed by 100% isodose line, dose to 90%, and 100% of clinical target volume (CTV); minimum, maximum, median, and average dose to both rectum and bladder are significantly higher with Fletcher applicator. Even if it is done, dose to both points B, minimum dose to CTV, and treatment time; dose to 2 cc (D2cc) rectum and rectal point etc.; D2cc, minimum, maximum, median, and average dose to sigmoid colon; D2cc of bladder remain significantly higher with this applicator. Dose to bladder point is similar (p > 0.05) between two applicators, after all optimization techniques. CONCLUSIONS: Fletcher applicator generates higher dose to both CTV and organs at risk (2 cc volumes) after all optimization techniques. Dose restriction to rectum is possible using graphical optimization only during selected HDR fractionation schedules. Bladder always receives dose higher than recommended, and 2 cc sigmoid colon always gets permissible dose. Contrarily, graphical optimization with ring applicators fulfills all dose volume objectives in all HDR fractionations practiced.

Intraluminal urethral brachytherapy for recurrence of transitional cell carcinoma of urinary bladder in urethral stump.

We report a unique case of successfully performed intraluminal brachytherapy for low volume urethral mucosal recurrence of transitional cell carcinoma urinary bladder, initially treated by transurethral resection of bladder tumor, followed by radical cystectomy. Since the patient was unwilling to undergo any other operational interventions, intraluminal brachytherapy of urethra was attempted. Fluroscopy guided intraluminal HDR brachytherapy using Lumencath(®) catheter under local anesthesia, and remote afterloading system (Nucletron, an Elekta company, Elekta AB, Stockholm, Sweden) was performed. A fraction dose of 7 Gy in seven weekly fractions was prescribed at 0.5 cm from the single applicator. The result was promising in terms of local control and symptomatic relief. Therefore, intraluminal brachytherapy in low volume superficial local disease in urethra may play a potential role, and should be applied when repeated surgery is not feasible due to technical or medical reasons.

Late nodal metastasis in early-stage node-negative oral cavity cancers after successful sole interstitial brachytherapy: an institutional experience of 42 cases in India.

PURPOSES: Brachytherapy, either alone or in combination with external irradiation, is a useful organ-preserving approach in the treatment of primary head and neck cancers. Treatment of regional nodal drainage area is not warranted in early-stage oral cavity cancers because T1N0 oral cavity cancers have less than 20% likelihood of nodal spread. We reviewed the records of interstitial brachytherapy cases of oral cavity cancers in our brachytherapy unit to assess the clinical outcome of the patients treated. METHODS AND MATERIALS: We tried to correlate the clinical outcome of the disease with different predictive factors for treatment outcome and to analyze statistically the role of these factors. RESULTS: Cases treated with combined external irradiation with interstitial brachytherapy included higher T stage, with greater risk for nodal spread, though initially node negative. As these were treated with microscopic dose for nodal clinical target volume, nodal recurrence was fewer (18.5%). On the contrary, although the early-stage (T1N0) oral cavity cancers that were treated with brachytherapy alone had initially a less than 20% chance of nodal metastasis, there was an increased risk up to 80% for late nodal metastasis after treatment. Tumor thickness >6mm (p=0.044) and need for a multiplanar implant (p=0.008) were found to be statistically significant risk factors for nodal recurrence. Other factors like high-grade tumors, ulcero-infiltrative lesions, implant of mobile tongue, and low hemoglobin, though relevant, were not found to be statistically significant. CONCLUSIONS: We recommend prophylactic nodal irradiation in addition to brachytherapy even for early-stage oral cancers treated with interstitial brachytherapy. Furthermore, the invasive procedure of interstitial brachytherapy causing a disruption of body's physiologic barrier to localize the disease is itself a probable risk factor for late nodal recurrence. Whether this, apart from the poor prognostic factors, causes increased chance of spread of a localized disease needs to be evaluated by a large prospective randomized study. This is needed to find out exactly the scenario where exclusive brachytherapy will be appropriate for treatment of early-stage oral cavity cancers.