Robotic SBRT in Prostate Cancer Patients Younger Than 50 Years Old-Updated Results

PURPOSE/OBJECTIVE(S)

Stereotactic Body Radiation Therapy (SBRT) is a standard therapeutic option for men with prostate adenocarcinoma. The median age of prostate cancer in the US is 66 but patients as young as 35 have been reported. Many younger patients will have surgery rather than SBRT for localized prostate cancer but some will be treated with SBRT. There is a paucity of data on the outcomes of this younger subset. This study reports updated outcomes on patients younger than 50 treated with SBRT at a single institution and compares outcomes to older patients.

MATERIALS/METHODS

Between April 2006 and December 2022, 6,130 patients with prostate cancer were treated with inhomogeneous-dosed SBRT using a robotic linear accelerator. Information was available for 4,143 patients. 3568 (86.12%) of patients were treated with a median dose of 3500cGY (3500-3625) delivered over 5 consecutive fractions prescribed to the 83-85% isodose line, and the remaining 575 (13.88%) other patients receiving a median dose of 4500cGY (4500-5400) to the pelvis in conventional fractionation followed by a 3 fraction SBRT boost of 2100 cGY (1950-2100) over 3 consecutive fractions. Androgen deprivation Therapy (ADT) was prescribed in 1,035 (24.98%) of these cases. The mean age was 67.4 years old. 48 patients were younger than 50 years old (mean age 46.6). 4,095 patients were 50 or older. Patients were divided into prognostic D'Amico risk groups with 43.75%, 50.00%, 6.25% of patients falling in the low, intermediate, and high-risk stratifications in the younger cohort and 23.88%, 57.05%, 19.07% in the older cohort respectively. Pretreatment PSA was 1.72 - 43.2 (median: 5.4) in the younger group and 0.3 - 661 (median: 6.5) in the older group. In the younger group, Gleason scores were 6 in 47.92%, 7 in 47.92%, and 8-10 in 4.16%. 44 younger patients were treated with SBRT alone. 4 patients also received supplemental external beam radiation (median dose 4500cGY) and 5 patients (10.42%) received Androgen Deprivation Therapy (ADT) as part of their treatment regimen. In the older group, Gleason scores were 6 in 29.84%, 7 in 54.14%, and 8-10 in 16.02%. 3522 were treated with SBRT alone. 573 patients also received supplemental external beam radiation (median dose 4500cGY) and 1030 patients (25.15%) received Androgen Deprivation Therapy (ADT) as part of their treatment.

RESULTS

At 75 months the 6-year biochemical relapse free survival was 95.83% in younger patients compared to 98.41% in older patients using the Phoenix definition of biochemical failure. The 6-year median post treatment PSA was 0.3 in younger patients and 0.2 in the older patients. There were no significant differences in the risk stratification between the 2 groups.

CONCLUSION

This represents the largest series evaluating outcomes in very young patients treated with definitive SBRT for prostate cancer. With updated 6-year follow up, SBRT remains an effective treatment for this younger subset of patients. Continued follow up will be required to see if these results remain durable.

The histone H1 variant accumulates in response to water stress in the drought tolerant genotype of Gossypium herbaceum L

We have optimized and improved the protocol for extraction of histone proteins from Gossypium herbaceum. Histone proteins were isolated by acid extraction method and fractionation of histone proteins were performed using RP-HPLC (reverse-phase high performance liquid chromatography). Analysis of histones from drought tolerant (Vagad) and drought sensitive genotype (RAHS-14) indicated that the tolerant genotype Vagad encodes a 29 kDa protein. Protein sequencing on MALDI TOF/TOF revealed that the 29 kDA protein shared sequence similarity with another drought-inducible linker histone-H1.S reported in tomato. This H1.S like linker histone was not found in RAHS-14 in our study. We further examined the expression of H1 variant at the transcript and protein levels and found that it was induced specifically in the tolerant genotype Vagad.

Analysis of chromatin structure in plant cells

A vast body of evidence in the literature indicates that nucleosomes can act as barriers to transcriptional initiation. The nucleosome at the promoter inhibits association of transcription factors disallowing active transcription of the gene. We have found a nucleosome on tobacco pathogenesis-related gene-1a (PR-1a) core promoter and mapped its boundaries and extension to find its span. The nucleosome covers the TATA box and Inr region of the core promoter and gets disassembled upon induction. Prior to its removal, modifications (i.e., acetylation and methylation of histones) occur at the nucleosome, proving a role of epigenetic modifications in transcriptional regulation. We summarize here various methodologies to analyze promoter chromatin structure in plants using the PR-1a core promoter as an example.

Genome wide expression profiling of two accession of G. herbaceum L. in response to drought

BACKGROUND

Genome-wide gene expression profiling and detailed physiological investigation were used for understanding the molecular mechanism and physiological response of Gossypium herbaceum, which governs the adaptability of plants in drought conditions. Recently, microarray-based gene expression analysis is commonly used to decipher genes and genetic networks controlling the traits of interest. However, the results of such an analysis are often plagued due to a limited number of genes (probe sets) on microarrays. On the other hand, pyrosequencing of a transcriptome has the potential to detect rare as well as a large number of transcripts in the samples quantitatively. We used Affymetrix microarray as well as Roche's GS-FLX transcriptome sequencing for a comparative analysis of cotton transcriptome in leaf tissues under drought conditions.

RESULTS

Fourteen accessions of Gossypium herbaceum were subjected to mannitol stress for preliminary screening; two accessions, namely Vagad and RAHS-14, were selected as being the most tolerant and most sensitive to osmotic stress, respectively. Affymetrix cotton arrays containing 24,045 probe sets and Roche's GS-FLX transcriptome sequencing of leaf tissue were used to analyze the gene expression profiling of Vagad and RAHS-14 under drought conditions. The analysis of physiological measurements and gene expression profiling showed that Vagad has the inherent ability to sense drought at a much earlier stage and to respond to it in a much more efficient manner than does RAHS-14. Gene Ontology (GO) studies showed that the phenyl propanoid pathway, pigment biosynthesis, polyketide biosynthesis, and other secondary metabolite pathways were enriched in Vagad under control and drought conditions as compared with RAHS-14. Similarly, GO analysis of transcriptome sequencing showed that the GO terms responses to various abiotic stresses were significantly higher in Vagad. Among the classes of transcription factors (TFs) uniquely expressed in both accessions, RAHS-14 showed the expression of ERF and WRKY families. The unique expression of ERFs in response to drought conditions reveals that RAHS-14 responds to drought by inducing senescence. This was further supported by transcriptome analysis which revealed that RAHS-14 responds to drought by inducing many transcripts related to senescence and cell death.

CONCLUSION

The comparative genome-wide gene expression profiling study of two accessions of G.herbaceum under drought stress deciphers the differential patterns of gene expression, including TFs and physiologically relevant processes. Our results indicate that drought tolerance observed in Vagad is not because of a single molecular reason but is rather due to several unique mechanisms which Vagad has developed as an adaptation strategy.

Analysis of histones and histone variants in plants

Histone proteins are the major protein components of chromatin - the physiologically relevant form of the genome (or epigenome) in all eukaryotic cells. For many years, histones were considered passive structural components of eukaryotic chromatin. In recent years, it has been demonstrated that dynamic association of histones and their variants to the genome plays a very important role in gene regulation. Histones are extensively modified during posttranslation viz. acetylation, methylation, phosphorylation, ubiquitylation, etc., and the identification of these covalent marks on canonical and variant histones is crucial for the understanding of their biological significance. Different biochemical techniques have been developed to purify and separate histone proteins; here, we describe techniques for analysis of histones from plant tissues.

Immunopathology of skin lesions

A study was conducted on 130 patients suffering from skin lesions which included psoriasis, lichen planus, DLE, pemphigus, vitiligo and alopecia areata. Forty age-and-sex-matched healthy individuals served as control. Serum IgG, IgM, and circulating immune complexes (CIC) were estimated. Significant increase in serum IgG (1937.2 +/- 1030.43 mg%) and IgM (232.12 +/- 136.98 mg%) was observed in all the skin lesions when compared with controls except in lichen planus where they were significantly lowered, values being 580.61+/- 77.35 mg% and 66.88 +/- 6.59 mg% respectively. CIC levels were significantly raised (P< 0.00 1) in various skin lesions (40.49+/-23.29) when compared with controls (17.68+/- 3.21), but no significance was observed in lichen planus( 17.72 +/- 4.28). Serum IgG, IgM and CIC were statistically significantly altered depending on the extent of the lesion and lowered significantly to almost normal values following treatment, thereby confirming the role of immunity in the pathogenesis of these skin disorders.