LAUSR

EDITORIAL The role of circulating and disseminated tumor cells in oncology treatment after curative surgery.7 Disseminat‐ ed tumor cells in the bone marrow can be a res‐ ervoir of cancer cells and may—after a period of dormancy—re ‐enter the vasculature and second‐ arily disseminate throughout the body.8 With no doubt, the study by Pach et al,6 which appeared in the current issue of Polish Archives of Internal Medicine (Pol Arch Intern Med), refers to nowadays valid issues related to DTCs. Results presented by the authors are, however, some‐ what unexpected: in left ‐sided colon and rectal cancers, the presence of DTCs in the bone mar‐ row seemed to diminish the risk of metastasis formation. There was also a trend toward im‐ proved survival in DTC ‐positive patients. This is contrary to the “gut feeling” supported in other studies,7 which suggested that dissemination of cancer cells in the bone marrow is a negative rath‐ er than positive prognostic factor. Furthermore, I found it interesting that the presence of DTCs in the bone marrow was not correlated with the depth of tumor infiltra‐ tion into the bowel wall and there was no increase in the risk of bone marrow positivity for DTCs in node ‐positive patients compared with those node‐ ‐negative. The presence of DTCs was not related to the tumor grade as well. This means that there was no correlation among DTCs in the bone mar‐ row and the most potent prognostic factors de‐ fined in the classic TNM system, ie, tumor size, lymph node metastases, and dedifferentiation of colorectal cancer. As a consequence of lack of cor‐ relation among DTCs and major classic prognos‐ tic factors (tumor size [T], node involvement [N], and histopathological grade), I found it not sur‐ prising that the authors were actually not able to attribute any clear prognostic value to the pres‐ ence of DTCs in terms of 5 ‐year survival (even af‐ ter excluding early stage, stage I, and advanced, stage IV, patients). There are 2 major strengths of the study by Pach et al6: 1) an attempt to include a homogenous With many tailored, patient ‐oriented molecular therapies developed in recent years, modern on‐ cology has become more and more individualized. Classic clinical entities we all were taught in med‐ ical schools are no longer valid as a base for ther‐ apeutic decisions. Colorectal cancer is an excel‐ lent example of the ongoing subclassification of the disease into smaller, narrower entities. Apart from the obvious anatomical distinction between right‐ and left ‐sided colon tumors, relevant bio‐ logical and molecular differences are well known nowadays, which has a significant impact on ther‐ apeutic decisions (TAbLE 1).1 Complex, multidisciplinary, and long ‐term on‐ cological treatment requires novel prognostic and predictive factors. These factors are needed to support clinical decisions by assessing prog‐ nosis in specific subgroups of patients and / or predicting their potential susceptibility to spe‐ cific high ‐end molecular therapies. Among many others, the prognostic and / or predictive value of circulating tumor cells (CTC) has been postulated and proven,2,3 also in patients with colorectal can‐ cer.4,5 Disseminated tumor cells (DTCs), studied by Pach et al,6 are a fraction of CTCs, which are capable of entering distant organs (like the bone marrow) and persisting there.2 Data on the prognostic value of CTCs are abun‐ dant,4,5 but evidence regarding the particular role of DTCs in colorectal cancer is not consistent. Dis‐ seminated colorectal cancer cells are present in peripheral blood in almost a half of patients with colorectal cancer with hepatic metastases, and in a quarter of this population, they can be found in the bone marrow too.6,7 Presence of DTCs in the bone marrow was shown to be an independent negative prognostic factor for overall survival in these patients. This observation supports the con‐ cept that DTCs present in the bone marrow indi‐ cate an increased tumor burden and, therefore, might serve as an additional individual mark‐ er for proper selection of patients for adjuvant EDITORIAL