Prostate Patterns of Care: Radiation and Surgical Treatment

What are we measuring and why?

This indicator measures the percentage of non-metastatic prostate cancer patients, aged 35 years and older, who received various forms of primary treatment by risk category (as per the GUROC Canadian Consensus definition). This indicator compares results for patients diagnosed in 2010 by participating provinces. Also, treatment patterns by patient age at diagnosis (=75 years of age and >75 years of age) are compared by risk category.

• Assessing patterns of care by risk category allows jurisdictions to examine their clinical practices against those in other jurisdictions. This knowledge may also help provinces enhance alignment with clinical guidelines.
• The type of treatment received by men with non-metastatic prostate cancer depends on their individual risk category (low-, intermediate- or high-) and other patient characteristics, such as age at the time of diagnosis as per the National Comprehensive Cancer Network (NCCN) guidelines (see the Risk Profile section in Chapter 2: Diagnosis and Staging for a description of prostate risk categories).¹ Analysis at the population-level may help evaluate treatment patterns and assess outcomes.
• Prostate cancer patients with non-metastatic disease may undergo curative primary treatment. This may involve radical prostatectomy (removal of the prostate gland along with nearby tissue) or radiation therapy, which may be administered with or without androgen deprivation therapy (ADT).¹ Some patients may undergo a combination of surgery and adjuvant (i.e., given after surgery) radiation therapy. Two types of radiation therapy are used: external beam radiation therapy (EBRT) and interstitial prostate brachytherapy. Prostate cancer patients may also be placed on active surveillance or watchful waiting, which allows them to delay or even avoid treatment (see “About Active Surveillance and Watchful Waiting”).
• Certain factors are known to increase the risk of cancer recurring after surgical removal of the prostate. These include positive resection margins (where cancer cells are found on the outer edges of the resected tumour). Rates of positive margins in men who have undergone surgery for prostate cancer have ranged from 10% to 36%.^2,3 Men whose surgeries leave positive margins may gain additional benefit from adjuvant radiation therapy. Radiation therapy may be administered early after surgery (generally within one year) in the case of adjuvant therapy or when PSA levels have risen, which is referred to as salvage therapy (generally after one year).

What are the results?

• Patterns of primary treatment for men with non-metastatic prostate cancer varied across the country, depending on men’s risk categories. Radical prostatectomy was the most commonly used treatment for men with low-risk prostate cancer in most provinces (Figure 4.21); radiation therapy was the most common primary treatment modality for low-risk patients in Prince Edward Island and British Columbia.
• For men in the high-risk group, treatment patterns were quite different: radiation therapy was the most common treatment modality.
• A considerable proportion of low-risk (41.5% to 76.4%) and high-risk (26.7 % to 56.6%) patients had no record of surgical or radiation treatment in the data. This was seen primarily among low-risk patients in Manitoba and Prince Edward Island, and among high-risk patients in Manitoba and Nova Scotia (Figure 4.21).
• Overall, among men who had surgery, only a small proportion received adjuvant radiation therapy (Figure 4.21).
• Figure 4.22 describes primary treatment patterns by patients’ age at diagnosis and risk category and shows the extent to which patient age influences treatment decisions. In general, most men over 75 years of age had no record of surgical or radiation treatment across all risk categories (Figure 4.23). Some exceptions were noted: for example, British Columbia reported a relatively high percentage of patients over 75 years of age who received some form of treatment across all risk groups. These findings may reflect a collaborative stage data quality issue (See Data and measurement considerations for more information on how risk profiles were derived).
• Compared to older men in intermediate- and high-risk categories, a greater proportion of low-risk men age 75 and under had no record of treatment. Prince Edward Island and Manitoba reported the highest percentage (72.9% and 71.1%, respectively) (Figure 4.22).
• Among men who received radiation therapy, low-risk prostate cancer patients were more likely to receive brachytherapy alone compared to intermediate- and high-risk patients (Figure 4.24). This finding is similar to results from previous studies.⁴ The highest proportionate use of brachytherapy in the low-risk group was in British Columbia; the lowest was in Saskatchewan (the data suggest no patients received brachytherapy in Nova Scotia during the time period of this analysis although some patients may have travelled out of province to access this treatment). Nearly all high-risk patients received external beam radiation therapy alone (Figure 4.24).

What do the results mean?

• Patterns of primary treatment for men with non-metastatic prostate cancer varied based on the risk category of the disease. Men with low-risk disease were most commonly treated with radical prostatectomy, while men with high-risk disease were most commonly treated with radiation therapy. These findings are comparable to a systematic review conducted by Sanyal et al. in 2013. Their study found that patients with low- to intermediate-risk profiles primarily received radical prostatectomy, while patients with a high-risk profile received radiation therapy.⁴ This variability in treatment patterns for men with prostate cancer should continue to be monitored to optimize outcomes.

Radical prostatectomy

• Radical prostatectomy rates varied depending on the patients’ risk category and age at diagnosis (Figures 4.21, 4.22 and 4.23). Surgery rates were highest among men in the intermediate-risk category (those aged 75 years and under). Rates of surgery were low (below 7.1%) among men over age 75 (data not shown).
• Previous studies found a relationship between surgical volume and patient outcomes; surgeons who perform higher annual volumes of radical prostatectomy have been associated with improved outcomes such as lower rates of positive surgical margins.⁵ Based on a steep surgical learning curve (i.e., it has been shown that a surgeon must perform at least 250 RPs to reach the plateau of the learning curve and to maximize cancer control) and the need for continuous practice, annual RP minimum volume thresholds have been suggested.⁶ For example, annual thresholds of 20 and 50 RPs have been proposed, but only a small proportion of surgeons in the United States and Europe reach these numbers.^7,8

No record of treatment (potentially active surveillance or watchful waiting)

• Based on data reported here, most men over age 75 had no record of treatment across risk categories. This was most pronounced in the low-risk group (Figure 4.23). It was determined that age 75 is an approximation for a current 10-year life expectancy, which evidence suggests should be the criterion for curative treatment.¹ This may explain the high percentage of patients over age 75 who had no record of treatment.
• These results are consistent with age-specific treatment patterns observed in other jurisdictions, including the United States. A recent American study showed that 61% of men aged 75 and older diagnosed with prostate cancer did not undergo surgery or radiation therapy.⁹
• While the actual percentage of prostate cancer patients on active surveillance or watchful waiting could not be captured and reported here, we could assume that at least a portion of low-risk prostate cancer patients with no record of treatment were on active surveillance or watchful waiting. Similarly, we could assume that a portion of high-risk patients were receiving ADT alone, and therefore would appear in the data under “treatment plan unknown.” ADT is a primary systemic therapy for men with advanced prostate cancer and is also used as neoadjuvant/concomitant/adjuvant therapy in combination with radiation therapy for men with non-metastatic disease.¹⁰

Adjuvant radiation therapy

• GUROC recommends that men who undergo radical prostatectomy have a consultation with a radiation oncologist soon after surgery to discuss the benefits and risks of adjuvant radiation therapy. If therapy is deemed appropriate (indications include positive surgical margin(s), Gleason score 8-10, extra-prostatic extension or seminal vesicle invasion), radiation therapy should begin within six months of surgery.^10,11
• Based on results reported here, only a small percentage of patients received adjuvant radiation therapy (Figure 4.21). If these data accurately reflect clinical practice, it may suggest that surgeons are not consistently referring patients to radiation oncologists following surgery.

Use of brachytherapy

• Brachytherapy involves placing radioactive material into the prostate gland, allowing the slow, targeted release of radiation. The use of brachytherapy varied across participating provinces (Figure 4.24). This may reflect differences among provinces in their eligibility criteria (i.e., by patient risk category).

References

1. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Prostate Cancer Version 2.2014. Chicago (IL): American Joint Committee on Cancer; 2014. 98 p.
2. Han M, Partin AW, Chan DY, Walsh PC. An evaluation of the decreasing incidence of positive surgical margins in a large retropubic prostatectomy series. J Urol. 2004 Jan;171(1):23-6.
3. Tyldesley S, Peacock M, Morris JW, So A, Kim-Sing C, Quirt J, et al. The need for, and utilization of prostate-bed radiotherapy after radical prostatectomy for patients with prostate cancer in British Columbia. Can Urol Assoc J. 2012;6(2):89-94.
4. Sanyal C, Aprikian AG, Chevalier S, Cury FL, Dragomir A. Direct cost for initial management of prostate cancer: a systematic review. Curr Oncol. 2013 Dec;20(6):e522-31.
5. Trinh Q-D, Bjartell A, Freedland SJ, Hollenbeck BK, Hu JC, Shariat SF, et al. A Systematic Review of the Volume–Outcome Relationship for Radical Prostatectomy. Eur Urol. 2013;64(5):786-98.
6. Steinsvik EA, Axcrona K, Angelsen A, Beisland C, Dahl A, Eri LM, et al. Does a surgeon’s annual radical prostatectomy volume predict the risk of positive surgical margins and urinary incontinence at one-year follow-up? Findings from a prospective national study. Scand J Urol. 2013 Apr;47(2):92-100.
7. Savage CJ, Vickers AJ. Low annual caseloads of United States surgeons conducting radical prostatectomy. J Urol. 2009 Dec;182(6):2677-9.
8. Vesey SG, McCabe JE, Hounsome L, Fowler S. UK radical prostatectomy outcomes and surgeon case volume: based on an analysis of the British Association of Urological Surgeons Complex Operations Database. BJU Int. 2012 Feb;109(3):346-54.
9. American Cancer Society. Cancer Treatment & Survivorship Facts & Figures 2014-2015. Atlanta (GA): American Cancer Society; 2014. 48 p.
10. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Prostate Cancer Version 1.2015. Chicago (IL); 2015.
11. Pickles T, Morgan S, Morton G, Souhami L, Warde P, Lukka H. Adjuvant radiotherapy following radical prostatectomy: Genito-Urinary Radiation Oncologists of Canada Consensus Statement. Can Urol Assoc J. 2008 Apr;2(2):95-9.