Optimizing the management of high-risk, localized prostate cancer

Magnetic nanoparticle hyperthermia enhances radiation therapy: A study in mouse models of human prostate cancer

PURPOSE

We aimed to characterise magnetic nanoparticle hyperthermia (mNPH) with radiation therapy (RT) for prostate cancer.

METHODS

Human prostate cancer subcutaneous tumours, PC3 and LAPC-4, were grown in nude male mice. When tumours measured 150 mm3 magnetic iron oxide nanoparticles (MIONPs) were injected into tumours to a target dose of 5.5 mg Fe/cm3 tumour, and treated 24 h later by exposure to alternating magnetic field (AMF). Mice were randomly assigned to one of four cohorts to characterise (1) intratumour MIONP distribution, (2) effects of variable thermal dose mNPH (fixed AMF peak amplitude 24 kA/m at 160 ± 5 kHz) with/without RT (5 Gy), (3) effects of RT (RT5: 5 Gy; RT8: 8 Gy), and (4) fixed thermal dose mNPH (43 °C for 20 min) with/without RT (5 Gy). MIONP concentration and distribution were assessed following sacrifice and tissue harvest using inductively coupled plasma mass spectrometry (ICP-MS) and Prussian blue staining, respectively. Tumour growth was monitored and compared among treated groups.

RESULTS

LAPC-4 tumours retained higher MIONP concentration and more uniform distribution than did PC3 tumours. AMF power modulation provided similar thermal dose for mNPH and combination therapy groups (CEM43: LAPC-4: 33.6 ± 3.4 versus 25.9 ± 0.8, and PC3: 27.19 ± 0.7 versus 27.50 ± 0.6), thereby overcoming limitations of MIONP distribution and yielding statistically significant tumour growth delay.

CONCLUSION

PC3 and LAPC-4 tumours represent two biological models that demonstrate different patterns of nanoparticle retention and distribution, offering a model to make comparisons of these effects for mNPH. Modulating power for mNPH offers potential to overcome limitations of MIONP distribution to enhance mNPH.

Do positive surgical margins predict biochemical recurrence in all patients without adjuvant therapy after radical prostatectomy?

Purpose

The objective was to study whether positive surgical margins (PSMs) predict biochemical recurrence (BCR) in all patients without adjuvant therapy after radical prostatectomy (RP).

Materials and Methods

We retrospectively reviewed the medical records of patients who underwent RP for prostate cancer at Veterans Health Service Medical Center from 2005 to 2011. BCR was defined by a prostate-specific antigen (PSA) value ≥0.2 ng/mL. The clinicopathological factors of the PSM group were compared with those of the negative surgical margin (NSM) group, and the predictive impact of a PSM for BCR-free survival were evaluated. In addition, we analyzed the prognostic difference for BCR-free survival between solitary and multiple PSMs.

Results

A PSM was noted in 167 patients (45.5%). BCR was reported in 101 men in total (27.5%). The BCR-free survival rate of the PSM group was lower than that of the NSM group (p<0.001). In a multivariate analysis for the total patients, PSM was significantly associated with BCR-free survival (p<0.001). After stratification by pathological T stage, Gleason score (GS), and preoperative PSA value, PSM was significantly predictive for BCR-free survival in men with pT2 and/or GS ≤6 or 7 and/or a PSA value <10 or 10-20 ng/mL (all p<0.05). Multiple PSMs were more predictive of BCR-free survival than was a solitary PSM (p=0.001).

Conclusions

A PSM is a significant predictor of postoperative BCR in patients with pT2 and/or GS ≤7 and/or preoperative PSA <20 ng/mL. Multiple PSMs are considered a stronger prognostic factor for prediction of BCR than is a solitary PSM.