Database Analysis Finds IMRT More Effective Than CRT and Proton Beam in Prostate Cancer

IMRT vs Proton Beam Therapy

Events per 100 person-years of follow-up*

IMRT

Proton

Morbidity

Bowel

12.2

17.8

Urinary non-incontinence

7.5

6.3

Urinary incontinence

3.1

3.3

Erectile dysfunction

6.6

7.4

Hip fracture

0.8

0.7

Cancer control

Additional cancer treatments

2.2

1.9

^*Propensity score adjustment was used to balance demographic, disease and institutional characteristics

Adapted from Sheets N, Goldin G, Meyer AM, et al. Comparative effectiveness of intensity modulated radiation therapy (IMRT), proton therapy and conformal radiation therapy in the treatment of localized prostate cancer. Presented at: 2012 Genitourinary Cancers Symposium presscast. January 31, 2012; San Francisco, CA.

Intensity-modulated radiation therapy (IMRT) was superior to conformal radiation therapy (CRT) in reducing recurrence and significant side effects in men with localized prostate cancer, according to a comparative effectiveness study based on the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. The study also found that proton beam therapy, the most expensive radiation modality available, did not improve outcomes as compared with IMRT.

Since 2000, use of IMRT has supplanted use of CRT. By 2008, almost 0% of prostate cancer patients who required radiation were treated with CRT, while nearly 100% received IMRT.

Senior author of the study, Ronald C. Chen, MD, MPH, University of North Carolina in Chapel Hill, said that there are few studies to directly compare radiation therapy options. “This study validated the change in practice, showing that IMRT better controls prostate cancer and results in fewer side effects,” he stated.

Chen spoke at a presscast about this study during the 2012 Genitourinary Cancers Symposium sponsored by the American Society of Clinical Oncology (ASCO), February 2-4, in San Francisco, California. Nathan Christopher Sheets, MD, presented the study at the ASCO GU Cancers Symposium.

IMRT vs CRT in Prostate Cancer

Events per 100 person-years of follow-up*

CRT

IMRT

Rate

Ratio

Morbidity

Bowel

14.7

13.4

.91

Urinary non-incontinence

8.8

8.8

Urinary incontinence

3.7

3.5

Erectile dysfunction

5.3

5.9

1.12

Hip fracture

1.0

0.8

0.78

Cancer control

Additional cancer treatments

3.1

2.5

0.81

^*Propensity score adjustment was used to balance demographic, disease, and institutional characteristics

IMRT indicates intensity-modulated radiation therapy; CRT, conformal radiation therapy

FISH indicates fluorescence in situ hybridization; CEP17, chromosome 17; IHC, immunohistochemistry.

Adapted from Sheets N, Goldin G, Meyer AM, et al. Comparative effectiveness of intensity modulated radiation therapy (IMRT), proton therapy and conformal radiation therapy in the treatment of localized prostate cancer. Presented at: 2012 Genitourinary Cancers Symposium presscast. January 31, 2012; San Francisco, CA.

The database included more than 12,000 patients with localized prostate cancer treated with CRT, IMRT, or proton beam therapy from 2002-2007.

IMRT significantly reduced the frequency of bowel effects (mainly rectal bleeding) from 14.7 per 100 person-years of follow-up to 13.4 (P <.001), although the effects on erectile dysfunction were increased in the IMRT-treated group from 5.3 per 100 person-years of follow-up to 5.9 in the IMRT group (P = .006). However, IMRT provided significantly superior cancer control, as reflected by the need for additional cancer treatment: 3.1 per 100 person-years of follow-up for CRT versus 2.5 in the IMRT group (P <.001).

When IMRT was compared with proton beam therapy, proton beam therapy was associated with a significant increase in bowel side effects (17.8 per 100 personyears of follow-up vs 12.2 for IMRT; P <.001). No significant difference in cancer control was observed between these two types of radiation.

“This type of comparative research is needed, because until now it has been unclear if newer treatments are better than older ones,” said Chen. “This study supports IMRT as current standard radiation for prostate cancer, with fewer side effects and improved cancer control versus the older CRT. Currently, there is no clear evidence that proton therapy is better than IRT.”

Presscast moderator Nicholas J. Vogelzang, MD, said, “There is no clear evidence that proton beam radiation is superior to other modalities, and given its cost and bowel effects, we must continue to study these modalities to determine their comparative risks versus benefits.” Vogelzang is chair and medical director of the Developmental Therapeutics Committee at US Oncology Research, Las Vegas, Nevada.

Sheets N, Goldin G, Meyer AM, et al. Comparative effectiveness of intensity modulated radiation therapy (IMRT), proton therapy and conformal radiation therapy in the treatment of localized prostate cancer. J Clin Oncol. 2012;30 (suppl 5; abstr 3).