The classification “TNM” allows to measure the characteristics of prostate cancer by combining the T indicators (degree of extension of the tumor), N (number and location of affected lymph nodes) and M (degree of spread of metastases) .
More complex systems have been developed to assess the actual state of cancer to define an appropriate treatment protocols and improve the development of the disease prognosis.
The “nomograms” (predictive statistical models) have been established from various parameters, to statistically predict the prognosis state, propagation and progression of cancer.
They were developed on large numbers of cases, from correlations between test results before and after treatment, to provide a predictive value to the results of previous examinations to treatment. Of these, the most used are the “Partin tables”, the “Kattan nomogram” (or “Memorial Sloan Kettering Cancer Center Nomogram”) and the “score Capra.”
Research in this area rising steadily with the introduction of new models and predictive parameters.
Use and need of nomograms
The chosen treatment should be proportionate to the degree of disease progression, the nomogram will therefore attempt to identify the best (the following examples are provided for information only): very low risk patients will not be the object that active surveillance; risk tumors low / intermediate will lead to localized treatments (surgery, radiotherapy …) those at intermediate risk / high will require the most aggressive treatments or new protocols.
The urologist will be able to offer his patient treatments tailored to his own illness, while allowing it to choose in full knowledge of his treatment.
The validity of the forecasts based on the choice of decision parameters, as well as the proper use of the nomogram.
Use the urologist will depend on the degree of confidence it gives them, because ultimately all have an indicative value.
Glossary related to nomograms
Over each of these parameters, the less favorable prognosis
Gleason score : indicator of cellular differentiation of tissue removed. Scores of primary and secondary Gleason: Gleason scores obtained from a biopsy is as the sum of the 2 most affected areas tumor, “primary score” and “high score” each of which can vary from 1 to 5 .
PSA: prostate specific antigen rate, substance secreted by the prostate that indicates tumor burden (the extent of cancer in the body).
Stadium: means the stage of cancer progression at diagnosis. T1c meant a non-palpable tumor by biopsy; T2a, palpable half prostatic lobe; T2b, on more than half a lobe; T2c, about 2; T3, extended outside the prostatic capsule; T4, with disseminated metastases.
Partin tables: They appoint the first nomogram relating to prostate cancer and the best known. Created in 1993 by Alan Partin, they have been seriously improved in 2011 by the John Hopkins Hospital (USA), thanks to a 5-year research, conducted on 5,000 patients who underwent prostatectomy.
Settings: These tables are based on the value of PSA, primary and secondary Gleason scores and on the stage of the tumor.
Partin tables reading method :
For each patient, the chosen table is that corresponding to its stage of tumor advancement. The line item is the one corresponding to the level of PSA and the column element to its Gleason scores. At the intersection of the row and the column thus defined, including the probability of the degree of extension of the tumor. The table in question also provides for a given confidence interval and for a population with the same parameters, the percentage with a potential extension given.
- PSA : 5
- Gleason Score : 7 (primary score 3 + secondary 4)
- Stadium table : T2a (palpable tumor on half prostatic lobe).
The table provides probabilities tumor confined to the prostate of 47%. Those of extraprostatic extension is 43%, the seminal vesicle of 7%, the lymph nodes of 2%.
In this example, then the proposed treatment should be a wide prostatectomy because it would lead, in the light of such results, in the probability of cure of about 90%. Additional treatments may be undertaken to improve such a probability.
Kattan nomogram (or Memorial Sloan Kettering Cancer Center nomogram)
Other nomogram has been developed, including one called “Kattan,” which is based on more parameters, but the results are presented in more summary form. The first data helped establish in 1999 (Kattan, Scardino and Wheeler); he subsequently enriched. The indicator is also able to assess the suites of treatment (prostatectomy, radiotherapy …) other predictions, such as the survival rate up to 15 years and the probability of recidivism to 10 years.
As the Partin tables, Kattan nomogram is based on the value of PSA, primary and secondary Gleason scores, staging (T, N, M) of the tumor. In addition, it takes into account the percentage of positive biopsies, the degree of invasion of the prostatic capsule, reaching seminal vesicle and / or lymph node and other personal information such as age, various information on health the patient or the treatment he has received.
Method of calculating the Kattan nomogram
The indicator assigns a value to each of these parameters it then associates to very complex formulas to arrive at an overall score. There are “calculators” or websites to inform the data of a patient and lead to the calculation of the various results of the nomogram.
Survival rate prediction sample
- Age: 62 years
- Health: 100% good
- Stages: T2a, N0 and M0 (no extraprostatic extension)
- Gleason scores: 7 (primary score 3 + 4 secondary)
- PSA: 22
The existing calculator on the Memorial Sloan Kettering Cancer Center website provides survival rate at 10 years 79%, and 15 years of 61% for cancer treatment.
Relevance of the nomogram
Studies, especially in 2008 in many international urological research centers, based on statistical data on more than 8,000 patients, have confirmed the relevance of the nomogram. Some studies show the excellence of its predictive value, 80% of neighbors. It was also proven that its use was still possible for patients at the extremes of risks.
Other nomogram has been developed, such as the University of California San Francisco (UCSF), called Score “Capra” (initials “Cancer of the Prostate Risk Assessment” or assessing the risk of prostate cancer) . It can be used for many suites of treatment, including this time in cases of active surveillance protocols or using cryotherapy.
It is based on the patient’s age, the value of PSA, primary and secondary Gleason score, stage of the tumor and the percentage of positive biopsies.
Unlike other nomogram, it calculates is very easy manner by assigning to each parameter to a value between 0 and 4 (as appropriate) and then summing all these values. The score obtained is a single number between 0 and 10.
Calculating Method of Capra score
Will be gradually added, for each parameter, 0 or the following values.
- Age: 50 years, add 1
- PSA: 6 to 10, add 1; 10 to 20, add 2; 20 to 30, add 3; over 30, add 4
- Primary Gleason Score: 4 or 5, add 3
- secondary Gleason score 4 or 5, add 1
- Stadium: T3, add 1
- Percentage of positive biopsies: more than 34%, add 1.
A score of Capra between 0 and 2 corresponds to a low risk; between 3 and 5, in an intermediate risk; greater than or equal to 6, to a high risk. Studies have shown that the risk level almost doubled with each increase of 2 points from the score of Capra.
- Age: 48 years
- PSA: 22
- Gleason score 7 (primary + secondary score 4 of 1 to 5)
- Percentage of positive biopsies less than 34%
- Stadium: T2
The patient would have a Capra score of 6. The risk is rather high and the therapeutic protocol will be defined accordingly.
Relevance of the nomogram Despite its simplicity, the score Capra is a similar accuracy to the best nomogram. It has been demonstrated by a study of over 10,000 patients who underwent prostate removal. Another European study published in 2012 and conducted on nearly 3,000 patients confirmed it, including those at the extreme scores. concordance indices relating to interest rate forecasts of recurrence and metastatic developments have proved them neighbors of 80%.
Partin Tables – Updates
Capra Kattan nomogram