Laurence Klotz

Dr. Laurence Klotz


Research Focus & Metrics

Academic Career Length

25Years (2002-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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20 January 2015 in Journal of Clinical Oncology
Verified
Journal Article
Closed access
LKLaurence Klotz
Laurence Klotz
DVDanny Vesprini
Danny Vesprini
PSPerakaa Sethukavalan
Perakaa Sethukavalan
VJVibhuti Jethava
Vibhuti Jethava
LZLiying Zhang
Liying Zhang
ALAndrew Loblaw
Andrew Loblaw
Purpose: Active surveillance is increasingly accepted as a treatment option for favorable-risk prostate cancer. Long-term follow-up has been lacking. In this study, we report the long-term outcome of a large active surveillance protocol in men with favorable-risk prostate cancer.Patients and Methods: In a prospective single-arm cohort study carried out at a single academic health sciences center, 993 men with favorable- or intermediate-risk prostate cancer were managed with an initial expectant approach. Intervention was offered for a prostate-specific antigen (PSA) doubling time of less than 3 years, Gleason score progression, or unequivocal clinical progression. Main outcome measures were overall and disease-specific survival, rate of treatment, and PSA failure rate in the treated patients.Results: Among the 819 survivors, the median follow-up time from the first biopsy is 6.4 years (range, 0.2 to 19.8 years). One hundred forty-nine (15%) of 993 patients died, and 844 patients are alive (censored rate, 85.0%). There were 15 deaths (1.5%) from prostate cancer. The 10- and 15-year actuarial cause-specific survival rates were 98.1% and 94.3%, respectively. An additional 13 patients (1.3%) developed metastatic disease and are alive with confirmed metastases (n = 9) or have died of other causes (n = 4). At 5, 10, and 15 years, 75.7%, 63.5%, and 55.0% of patients remained untreated and on surveillance. The cumulative hazard ratio for nonprostate-to-prostate cancer mortality was 9.2:1.Conclusion: Active surveillance for favorable-risk prostate cancer is feasible and seems safe in the 15-year time frame. In our cohort, 2.8% of patients have developed metastatic disease, and 1.5% have died of prostate cancer. This mortality rate is consistent with expected mortality in favorable-risk patients managed with initial definitive intervention.

1 January 2010 in Journal of Clinical Oncology
Verified
Journal Article
Closed access
LKLaurence Klotz
Laurence Klotz
LZLiying Zhang
Liying Zhang
ALAdam Lam
Adam Lam
RNRobert Nam
Robert Nam
AMAlexandre Mamedov
Alexandre Mamedov
ALAndrew Loblaw
Andrew Loblaw
Purpose: We assessed the outcome of a watchful-waiting protocol with selective delayed intervention by using clinical prostate-specific antigen (PSA), or histologic progression as treatment indications for clinically localized prostate cancer.Patients and Methods: This was a prospective, single-arm, cohort study. Patients were managed with an initial expectant approach. Definitive intervention was offered to those patients with a PSA doubling time of less than 3 years, Gleason score progression (to 4 + 3 or greater), or unequivocal clinical progression. Survival analysis and Cox proportional hazard model were applied to the data.Results: A total of 450 patients have been observed with active surveillance. Median follow-up was 6.8 years (range, 1 to 13 years). Overall survival was 78.6%. The 10-year prostate cancer actuarial survival was 97.2%. Overall, 30% of patients have been reclassified as higher risk and have been offered definitive therapy. Of 117 patients treated radically, the PSA failure rate was 50%, which was 13% of the total cohort. PSA doubling time of 3 years or less was associated with an 8.5-times higher risk of biochemical failure after definitive treatment compared with a doubling time of more than 3 years (P < .0001). The hazard ratio for nonprostate cancer to prostate cancer mortality was 18.6 at 10 years.Conclusion: We observed a low rate of prostate cancer mortality. Among the patients who were reclassified as higher risk and who were treated, PSA failure was relatively common. Other-cause mortality accounted for almost all of the deaths. Additional studies are warranted to improve the identification of patients who harbor more aggressive disease despite favorable clinical parameters at diagnosis.

21 November 2008 in BJU International
Verified
Journal Article
Closed access
PDF file
LKLaurence Klotz
Laurence Klotz
LBLaurent Boccon‐Gibod
Laurent Boccon‐Gibod
NSNeal D. Shore
Neal D. Shore
CACal Andreou
Cal Andreou
BPBo‐Eric Persson
Bo‐Eric Persson
FSFritz H. Schröder
Fritz H. Schröder

1 April 2021 in JAMA Oncology
Verified
Journal Article
Open access
PDF file
LKLaurence Klotz
Laurence Klotz
JCJoseph Chin
Joseph Chin
PBPeter C. Black
Peter C. Black
AFAntonio Finelli
Antonio Finelli
MAMaurice Anidjar
Maurice Anidjar
MHMasoom A. Haider
Masoom A. Haider
For 35 years, the standard pathway for prostate cancer diagnosis has been systematic transrectal ultrasonography biopsy (TRUSBx) of the prostate in patients with elevated prostate-specific antigen (PSA) levels. Transrectal ultrasonography is used primarily for anatomic guidance, as traditional ultrasonography discriminates poorly between cancerous and noncancerous tissue.1

1 April 2015 in Journal of Clinical Oncology
Verified
Journal Article
Closed access
LKLaurence Klotz
Laurence Klotz
COChris O'CAllaghan
Chris O'CAllaghan
KDKeyue Ding
Keyue Ding
PTPaul Toren
Paul Toren
DDDavid Dearnaley
David Dearnaley
JCJuanita M. Crook
Juanita M. Crook
Purpose: Three small retrospective studies have suggested that patients undergoing continuous androgen deprivation (CAD) have superior survival and time to progression if lower castrate levels of testosterone (< 0.7 nmol/L) are achieved. Evidence from prospective large studies has been lacking. Patients and Methods: The PR-7 study randomly assigned patients experiencing biochemical failure after radiation therapy or surgery plus radiation therapy to CAD or intermittent androgen deprivation. The relationship between testosterone levels in the first year and cause-specific survival (CSS) and time to androgen-independent progression in men in the CAD arm was evaluated using Cox regression. Results: There was a significant difference in CSS (P = .015) and time to hormone resistance (P = .02) among those who had first-year minimum nadir testosterone ≤ 0.7, > 0.7 to ≤ 1.7, and ≥ 1.7 nmol/L. Patients with first-year nadir testosterone consistently > 0.7 nmol/L had significantly higher risks of dying as a result of disease (0.7 to 1.7 nmol/L: hazard ratio [HR], 2.08; 95% CI, 1.28 to 3.38; > 1.7 nmol/L: HR, 2.93; 95% CI, 0.70 to 12.30) and developing hormone resistance (0.7 to 1.7 nmol/L: HR, 1.62; 95% CI, 1.20 to 2.18; ≥ 1.7 nmol/L: HR, 1.90; 95% CI, 0.77 to 4.70). Maximum testosterone ≥ 1.7 nmol/L predicted for a higher risk of dying as a result of disease (P = .02). Conclusion: Low nadir serum testosterone (ie, < 0.7 mmol/L) within the first year of androgen-deprivation therapy correlates with improved CSS and duration of response to androgen deprivation in men being treated for biochemical failure undergoing CAD.

1 March 2020 in European Urology
Verified
Journal Article
Closed access
LKLaurence Klotz
Laurence Klotz
GPGreg Pond
Greg Pond
ALAndrew Loblaw
Andrew Loblaw
LSLinda Sugar
Linda Sugar
MMMadeline Moussa
Madeline Moussa
MHMasoom Haider
Masoom Haider