What does a prostate cancer pathology report showing Gleason score (GS) 4+3 and low Decipher score imply for external beam radiation therapy (XRT) staging and treatment planning?

Management of Gleason Score 4+3 Prostate Cancer with Low Decipher Score for External Beam Radiation Therapy

For a patient with Gleason score 4+3 prostate cancer and a low Decipher score, external beam radiation therapy (XRT) is an appropriate treatment option with excellent long-term disease control rates. 1

Risk Stratification and Implications

• A Gleason score of 4+3=7 places the patient in the intermediate-risk category for prostate cancer according to established guidelines 2, 1
• The predominant pattern 4 (in 4+3) indicates a more aggressive disease than 3+4=7, with potentially higher risk of progression compared to lower Gleason scores 2, 3
• A low Decipher score is a favorable genomic biomarker that suggests a lower risk of metastasis despite the intermediate-risk Gleason score classification 2, 1

Treatment Planning for XRT

• For intermediate-risk prostate cancer with Gleason 4+3, external beam radiation therapy should be delivered using conformal techniques to a minimum target dose of 70-79 Gy given in 1.8-2.0 Gy fractions 2
• Treatment options for this patient include:
  • External beam radiation therapy alone with dose escalation to 78-79 Gy 2
  • External beam radiation therapy with short-course (6 months) androgen deprivation therapy 2, 1
• CT-based treatment planning is essential for precise targeting of the prostate and seminal vesicles while minimizing radiation exposure to the bladder, rectum, and small bowel 2

Role of the Decipher Score

• The low Decipher score provides additional prognostic information beyond the Gleason score and suggests a more favorable outcome 2, 1
• This genomic classifier helps identify patients who may have less aggressive disease despite having intermediate-risk features on standard pathology 2
• The combination of Gleason 4+3 with a low Decipher score may allow for consideration of less intensive treatment approaches compared to patients with similar Gleason scores but high Decipher scores 1

Treatment Recommendations Based on Risk Factors

• For this specific combination (Gleason 4+3 with low Decipher score), consider:
  • Dose-escalated external beam radiation therapy (78-79 Gy) using 3D conformal techniques with at least four fields and a margin of no more than 10mm at the prostatic rectal interface 2
  • Short-course (6 months) androgen deprivation therapy may be added, particularly if there are other adverse features such as PSA >10 ng/mL 2
• Modern radiation techniques such as intensity-modulated radiation therapy (IMRT) or image-guided radiation therapy (IGRT) should be utilized to maximize treatment precision 2, 4

Monitoring and Follow-up

• After external beam radiotherapy, serum PSA should reach 1 ng/mL within 16 months 1
• First follow-up visit should be at 3 months after treatment, including PSA measurement, digital rectal examination, and assessment of treatment-related symptoms 1
• Regular follow-up at six-month intervals for five years and annually thereafter is recommended for oncological outcome assessment 2

Potential Pitfalls and Considerations

• Despite the low Decipher score, Gleason pattern 4 is still associated with malignant behavior and should not be undertreated 5
• Patients should be informed that androgen deprivation therapy with radiation increases adverse effects on sexual function 1
• Radiation dose accuracy and escalation provide proven improvements in local tumor control and reduction in late radiation-related complications 2
• Patients with obstructive urinary symptoms may experience exacerbation with radiation therapy and should be evaluated carefully before treatment 1