Yale formula (update of the Roach formula).
A new formula for prostate cancer lymph node risk
Many investigators have created tools for predicting extraprostatic disease and lymph node (LN) involvement. One widely used tool is a linear formula created by Roach et al. the Roach formula (RF), which defines the risk of pelvic LN as follows: (% pelvic LN risk = prostate-specific antigen [PSA])2/3 + (Gleason – 6))10). There has been significant stage migration in prostate cancer over the past decade since the creation of the RF. To provide clinicians with a practical approach to estimating LN risk that was developed from a population-based sample of patients who reflect the vast majority of patients diagnosed in the modern PSA era, and whose care reflects current patterns of care, we developed and validated a new predictive formula using the SEER database. A fast, accurate, and easy-to-use formula would be helpful in discussing LN risk with patients and in the conceptualization of LN risk for future clinical trials.
Research authors: James B. Yu, Danil V. Makarov, Cary Gross
Details Formula Study characteristics Files & References
Model author
Model ID
Revision date
MeSH terms
  • Lymphadenectomy
  • Prostate Cancer
  • Prostate Specific Antigen
  • Gleason Score
  • Lymph Nodes
  • Dissection
  • Model type
    Custom model (Calculation)

    Additional information

    The SEER database was investigated for patients treated in 2004 through 2006. The SEER database is a large national cancer database that encompasses more than 26% of the United States population. Since 2004 it has included pretreatment PSA and pretreatment clinical stage, along with detailed pathologic information, as part of
    its standardized data collection (13). We identified 150,012 prostate cancer patients diagnosed from 2004 to 2006 within the SEER database. We excluded patients if they did not receive a radical prostatectomy, if prostate cancer was not their first and only malignancy, if their histology was other than adenocarcinoma, if they received preoperative radiation, if theirclinical stage was recorded as cT2 without further specification, or if they had missing
    or incomplete or discordant clinical or pathologic data. Patients for whom prostate cancer was not their first and only malignancy were excluded to prevent the erroneous attribution of non–prostate cancer positive LNs to the original prostate cancer diagnosis. We also excluded patients if they had clinical stage cT1a or cT1b, or had cT3 or cT4 or clinically metastatic disease, to reflect the most common clinical situations of cT1c, cT2a, cT2b, and cT2c disease
    and to improve the accuracy of our potential formula.
    Formula was made using 1460 patients to build it and 1470 patients to validate it. 

    Study Population

    Total population size: 2930
    Males: {{ model.numberOfMales }}
    Females: {{ model.numberOfFemales }}

    Categorical characteristics

    Name Subset / Group Nr. of patients
    Race White 2518
    Black 244
    American Indian/Alaska Native 4
    Other unspecified 4
    Unknown 23
    Age (y, median = 61) <50 198
    50-59 1085
    60-69 1327
    70-79 316
    80+ 4
    Gleason score 6 and lower 1079
    7 1431
    8 210
    9 205
    10 5
    Clinical stage T1c 2126
    T2a 215
    T2b/T2c 589
    Preoperative prostate specific antigen 0-2.5 164
    2.6-4.0 304
    4.1-6.0 1076
    6.1-10 900
    10.1-25.9 486
    Pathological stage Organ confined 1936
    Extraprostatic extension 725
    Seminal vesicle invasion 108
    Lymph node involvement 136
    pT4 25
    Number of lymph nodes examined pathologogically 10-15 1868
    16-20 575
    21-30 392
    31-56 95
    Yale formula (update of the Roach formula).
    Refer to Intended Use for instructions before use
    Evidencio B.V., Irenesingel 19, 7481 GJ, Haaksbergen, the Netherlands

    Related files

    No related files available

    Supporting Publications

    Notes are only visible in the result download and will not be saved by Evidencio

    The calculated probability of lymph node involvement is: %

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    Outcome stratification

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    Conditional information

    Result interpretation

    Reported sensitivity is 39% and specificity is 94,9%.
    Compared to the Roach Formula (RF) and Nguyen Formula (NF), our Yale Formula (YF) was able to classify the most patients in the high-risk (>15%) group while still maintaining good PPV and specificity. The YF had the best combination of sensitivity with high specificity and did not underestimate LN risk as the NF did. Underestimation of LN risk is potentially more harmful than overestimation of risk if patients are counseled to undergo prostate-only therapy based on an underestimation of risk, whereas they could potentially undergo pelvic LN irradiation with a chance at improving subsequent pelvic and cure rates. The utility of pelvic radiotherapy remains controversial, but it stands to reason that pelvic radiotherapy should be given more often to patients at higher risk for LN metastases than to those who are at lower risk.

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    Calculations alone should never dictate patient care, and are no substitute for professional judgement. See our full disclaimer.

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    C-Index: | 95% CI: 0.6624 - 0.7318

    Validation author: T. A. Hueting

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