Focal Boosted IMRT Treatment of Prostate Cancer to 84 Gy in 28 Fractions: Preliminary Clinical Outcomes and Dosimetry

PURPOSE/OBJECTIVE(S)

The FLAME trial reported that focal boosting of prostate tumor to 95 Gy in 35 fractions improves biochemical control. However, this treatment is not commonly used in the United States. We investigated a focally boosted treatment of 84 Gy in 28 fractions (EQD2 108 Gy, BED 252 Gy).

MATERIALS/METHODS

Between 2019-2022, men with unfavorable intermediate risk (uIR) and high risk (HR) prostate cancer were enrolled on a prospective registry and received a novel IMRT regimen. The dose levels were 84 Gy to the gross tumor volume (GTV) as defined on mpMRI (T2W and ADC) with no added margin, 70 Gy to the prostate and proximal seminal vesicles, and optional 50.4 Gy to elective pelvic lymph nodes (all 28 fractions). Patients received fiducial markers and hydrogel spacer. The treatment planning goal was to cover 95% of the GTV at 84 Gy, and also meet the target and normal tissue dosimetry criteria of the hypofractionated treatment arm of NRG-GU005. VMAT was used for treatment delivery. ADT was given at the discretion of the treating physician.

RESULTS

A total of 20 men were included in the study, 2 (10%) uIR and 18 (90%) HR. 9 (45%) tumors were GS 7, 7 (35%) were GS 8, and 4 (20%) were GS 9. There were 13 (65%) stage cT1, 4 (20%) cT2 and 3 (15%) cT3. One (5%) patient received short term ADT, 18 (95%) long term ADT, and 1 (5%) refused ADT. 18 (90%) men received elective nodal radiation. The mean baseline PSA was 25.1 (range 4.2-73.4). The median baseline IPSS score was 11.1 (IQR 4.5-12), and 4 patients had severe baseline urinary symptoms (IPSS ≥20). The mean baseline prostate volume was 57.4 cc (range 26.8-198.3). The mean volume of the 84 Gy boost target was 7.1 cc (range 2.3-15.0) and the mean proportion of the prostate boosted was 14.8% (range 2% - 47%). There were 10 (50%) men with 1 boost target, 6 (30%) with two, 3 (15%) with three, and 1 (5%) had 4 boost targets. Targets were located in peripheral zone (85%), transition zone (30%), and central zone (5%). Patients met all per-protocol normal tissue criteria of NRG-GU005, except for bladder D0.03cc. The mean±SD (Gy) rectum D15%, D25%, and D30% were 51±5, 45±5, 42±4. The mean±SD (Gy) bladder D0.03cc, D30%, D50% were 79±4, 50±8, 38±10. At a median follow up time of 21.3 months (range 7.1-38.2), no patients have developed biochemical progression, local recurrence, distant progression, or death from prostate cancer. One patient died at 18 months from metastatic colorectal cancer, unrelated to prostate cancer treatment. Acute grade 1-2 GU toxicity occurred in 13 (65%) patients, and acute grade 1-2 GI toxicity occurred in 4 (20%) patients. No patients developed grade 3+ acute or late GU or GI toxicity. Two patients required temporary foley catheter for obstruction during RT, and both had IPSS >20 at baseline. The patient who refused ADT had a PSA bounce of magnitude 2.2 ng/mL at 14 months, PSA values declined without additional treatment.

CONCLUSION

A novel 28-fraction focal boosted IMRT treatment is feasible and has an acceptable early toxicity profile. Oncologic results are promising but require longer follow up.

Role of circulating tumor cells (CTCs) in biochemical recurrence (BR) of prostate cancer

60

Background: CTCs have an established role in the prognosis of metastatic prostate cancer. Little data exists regarding the role of CTCs in BR of prostate cancer. The aim of this study was to determine whether there is a correlation between the number of CTCs in men with BR with varying prostate specific antigen (PSA) and PSA doubling time (PSADT) categories. Secondary endpoints looking at correlation of the CTCs with clinical or laboratory factors (Gleason scores, testosterone, hemoglobin, alkaline phosphatase, BMI, imaging results) will also be assessed.

Methods: BR was defined as patients (pts) who have undergone primary treatment with prostatectomy or radiation or both, with rise to >/= 0.2 from a prior undetectable level for prior prostatectomy or > 2 mg/dl rise from post-nadir radiotherapy. The study was powered to detect a Pearson correlation of .46 with a sample size of 36. Eleven of planned accrual goal of 36 pts were enrolled from May to September 2010. PSADT was obtained and correlated with the CTC values, categorized as PSADT of < 3 months, 3-14.9 months and > 15 months. CTCs were evaluated in 7.5 mL of peripheral blood using the CTC CellSearch test.

Results: The median age for 11 patients was 75 y/o (range: 57-91) with a median PSA of 1.6 ng/mL (range 0.2-6.5) and testosterone levels of 309 ng/dL (range: 31–471). Gleason scores were 8 (n=1), 7 (n=5), 6 (n=2), 5 (n=3). Prostatectomy was the primary treatment in 6 pts, radiotherapy in 5 pts and Cyberknife in 1 pt. Median hemoglobin was 12.43 g/dL, BMI was 26.79 and alkaline phosphatase was 69 IU/L. PSADT varied between 3 to 55 months. All pts accrued had 0 CTC levels. The latter result translates into a 95% confidence interval upper bound of approximately .27 for the proportion of patients in this population who have non-zero CTC levels.

Conclusions: Prostate cancer pts with BR have negative blood CTCs and does not appear to correlate with PSA or PSADT. However, the limited number of patients precludes sufficient interpretation at this time and further accrual is ongoing. The absence of CTC levels in this patient population, if supported through further data collection, could emerge as an important unanticipated finding from this study. Supported by IRG-08-091-01 from ACS to GWU Cancer Institute.

No significant financial relationships to disclose.

Preneoplastic lesions of the prostate-clinical, pathological and molecular biological aspects

Needle biopsy is the mainstay of definitive diagnosis of prostate cancer (PCA). While prostate-specific antigen (PSA) screening has facilitated early diagnosis of PCA, it has also resulted in an increase in the proportion of prostate biopsies showing various preneoplastic lesions (PNLs). At times such lesions are the sole finding in the limited amount of tissue available for assessment in an individual biopsy. Hence accurate identification of these lesions is important to avoid errors in the diagnosis of prostatic malignancy and in patient management. Furthermore, some interesting observations have been made regarding the molecular biological aspects of various PNLs during the last decade. In parallel with anatomic and physiological differences in various human races, racial differences have also been observed regarding the incidence of prostatic intra-epithelial neoplasia. This review focuses on prostatic intraepithelial neoplasia (PIN), atypical adenomatous hyperplasia (AAH) and atypical prostatic glands or atypical small acinar proliferation (ASAP) as putative preneoplastic lesions of the prostate. These lesions are reviewed with reference to their overall incidence, histopathological findings, histological differential diagnosis, clinical significance and molecular biological aspects.

Simultaneous microsurgical vasal reconstruction and varicocele ligation: safety profile and outcomes

OBJECTIVES

Simultaneous varicocele ligation and vasal reconstruction has previously been avoided because of concern regarding testicular devascularization. This study sought to investigate the safety of a simultaneous combined approach in the hands of an experienced microsurgeon.

METHODS

A retrospective review was conducted of the records of 47 men who underwent vasal reconstruction, 10 (21%) of whom had simultaneous ligation of a clinically palpable varicocele. Specific attention was focused on the development of postoperative testicular atrophy and hydrocele and the analysis of postoperative semen parameters.

RESULTS

No patient developed postoperative testicular atrophy or hydrocele. No statistically significant difference existed in postoperative seminal parameters between those patients who had vasal reconstruction alone and those who had a combined procedure.

CONCLUSIONS

In the hands of an experienced microsurgeon, simultaneous vasal reconstruction and varicocele ligation is a management strategy that has an excellent safety profile. This approach is not recommended for the occasional microsurgeon.