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10.1245/s10434-006-9253-z
Annals of Surgical Oncology 14:362-364 (2007)
© 2007 Society of Surgical Oncology
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Original Article

Prognostic Score in Gastric Cancer Patients

Daniele Marrelli, MD and Franco Roviello, MD

Department of Human Pathology and Oncology, Unit of Surgical Oncology, University of Siena, Siena, Italy

Correspondence: Address correspondence and reprint requests to: Daniele Marrelli, MD. Policlinico Le scotte, Viale Bracci, 53100 Siena, Italy; E-mail: Marrelli{at}unisi.it

Key Words: Gastric cancer • Prognostic score

We read with great interest the article by Dr. Costa and coworkers,1 entitled "Prognostic score in gastric cancer: the importance of a conjoint analysis of clinical, pathologic, and therapeutic factors". The utility of a prognostic score consists in the possibility to consider simultaneously all potential prognostic variables, thus assigning a percentage of risk to each patient. For this reason, the use of prognostic indexes is increasing in clinical oncology. The authors have conducted a retrospective analysis of a large number of potential prognostic factors on 230 consecutive patients. By multivariate analysis, six independent risk factors were identified, and the corresponding beta-coefficients were used to obtain a risk score for each patient. We have some comments about the methods used and the results obtained in this study:

  1. About 20% of patients were submitted to non-curative surgery. The prognosis of gastric cancer in the patients with residual tumor is generally poor, independently of other potential prognostic variables.2–4 However, multivariate analysis did not identify residual tumor as statistically significant. How were non-curative operations distributed in the different prognostic groups?
  2. We recently conducted a prospective computation of a prognostic score in the patients submitted to curative surgery at three Surgical Departments of the Italian Research Group for Gastric Cancer (IRGGC).5 In our study, the score was calculated by including the regression coefficients of prognostic variables in an exponential formula, which can be easily applied to database programs.6–9 This allowed two important points: (a) a linear definition of the risk of recurrence, rather than the inclusion of the patients in a risk category; (b) due to the exponential equation, the relative weight of prognostic variables is balanced with the overall risk of single patient. For example, in the study by Dr. Costa and coworkers, patients with early gastric cancer treated by D0 or "non-standard" lymphadenectomy obtain a minimum score of 3.5, and as a consequence they should be included in group 2, with a very low five-year survival probability (49%). Similarly, female patients staged IIIa may have a 91% survival probability, whereas males with the same prognostic factors obtain a 49% survival rate. Could gender play such an important role in the determination of prognosis of stage IIIa patients? According to the IRGGC score, in a pT1N0 patient (lower third, age 60) the risk or recurrence changes from 9% after D1 lymphadenectomy to 4% after D2–D3. On the contrary, the impact of an extended lymphadenectomy may be clearly higher in cases with an intermediate prognosis such as pT2N1, with a reduction of the risk probability from 61% (D1) to 39% (D2–D3). Again, in very high risk groups (pT3N2), only a slight decrease of the risk from 94% in D1 to 87% in D2–D3 lymphadenectomy is obtained. This modulated effect is similar for all other variables of the IRGGC prognostic score. Could the use of an exponential formula be associated with a better calibration between the predicted and observed risk in the study by Dr. Costa and coworkers?
  3. The inclusion of non-curative operations could have involved an excessive prognostic weight of lymph node dissection if we assume that most patients treated by R1/R2 surgery were submitted to D0 or non-standard lymphadenectomy. In addition to the statistical method of score calculation, this may have caused the discrepancy between the score and the expected prognosis in some potential groups such as pT1 category with D0 dissection. Even if probably only few patients with pT1 tumors were treated by D0 or nonstandard lymphadenectomy in the present study, this aspect may be particularly important when applying the prognostic score in different clinical settings. The inclusion of only potentially curative resection may perhaps allow a better correspondence between predicted and observed prognosis.
  4. In the IRGGC prognostic score nine potential prognostic variables were considered, a number similar to other scores for gastric cancer proposed in the literature;10–13 nodal status, depth of invasion, extent of lymphadenectomy, tumor location and patient age resulted as statistically significant. In the study of Dr. Costa and coworkers, a larger number of potential prognostic variables (25 covariates) were evaluated by statistical analysis; some of these variables are highly collinear (i.e., pT and pN classes with pTNM stage). Furthermore, stage I and stage II were included in the same group, and as a consequence patients with different prognosis such as pT1N0, pT2N1 and pT3N0 were grouped in the same category. This may be consistent with the data and statistical analysis of the present study, but probably not in different series. All these factors, together with potential bias in the distribution of covariates due to the low number of patients, may have produced unexpected results such as a high prognostic power of gender and lymphocyte count, and the exclusion of well-demonstrated prognostic variables such as surgical curability, resection margin and tumor location. 2,5,10,12,13
  5. The clinical utility of a prognostic score may be higher if it is able to allocate most cases in the high-risk and low-risk groups, thus reducing the number of patients with an intermediate prognosis. In the IRGGC prognostic score, in which a linear definition of the risk was obtained, only 18% of cases were regarded as patients with an intermediate prognosis (risk score from 30 to 60). Furthermore, two large groups of patients with a "0" risk or a "100%" risk were identified. A large prospective study involving several centers of the IRGGC is ongoing in order to validate these results. In the study from Dr. Costa and coworkers, we noted that many patients were classified into groups 2 and 3, and the number of patients in that groups was similar to the number of cases in stages IIIa and IIIb. How many patients from stages IIIa and IIIb were shifted to groups 1 and 4, i.e. to the groups with very good or poor prognosis?

Finally, we would sincerely congratulate Dr. Costa and coworkers for their contribution to a better definition of prognosis of gastric cancer patients. We believe that external prospective studies comparing the different prognostic score proposed in the literature may represent an essential step for this important issue.

Received for publication July 19, 2006. Accepted for publication September 28, 2006.


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