Estudio de casos y controles de marcadores sanguíneos para el diagnóstico precoz de cáncer de mama

Resum

Breast cancer is the most common female malignancy and the leading cause of death in the developed world. Screening programmes for the early detection contribute to an early diagnosis of the disease and therefore to improving survival. There are no tumour- specific markers for the early stage of breast cancer. In fact, if there was an effective marker, then it would help build support for the radiological screening. However, many markers are requested in the phase of clinical study and final diagnosis without any clinical criteria. Clinical guidelines recommend against the use of tumour markers in breast cancer, except for the Ca 15.3 which is used to monitor the effectiveness of the oncological treatment. Our objective was to determine the real usefulness of a series of routine tumour markers in the initial pre-surgical phase of breast cancer, in addition to investigating other less known experimental markers. Furthermore, an epidemiological study of the samples was performed. A case-control study was conducted among 63 patients with local breast cancer, no relapses and pending surgery, and another 63 healthy women. We determined the detection of routine markers (Ca 15.3, CEA, Ca 125, Ca 19.9, NSE, Cyfra 21.1, alpha fetoprotein) and experimental markers (INGAL, EGFR and 8-OH-dG). We analyzed the epidemiological characteristics of both series and we also determined the vitamin D levels. Significant differences were found in patients with higher levels of Ca 15.3, Cyfra, NSE and CEA. However, considering cut-off values, the Ca 15.3 marker would be the only significant one, although with low sensitivity. In relation to the experimental markers, we found significant results in the highest levels of EGFR in the controls, and in the highest levels of 8-OH-dG in the cases. In the epidemiological study, the following were significant risk variables: age, menopause, unemployment, BMI and low levels of vitamin D, although the latter is related to the BMI. The current use of tumour markers is unjustified and inefficient in the breast cancer diagnosis phase or early phase. We identified, for the first time, the existence of a probably effective marker for breast cancer early phases, which is the 8-OH-dG marker. It would be highly desirable to plan new global studies in this fine of investigation which we have initiated. Age, menopause, unemployment, BMI and low levels of vitamin D are factors associated with the breast cancer development. These factors should be included in large epidemiological studies in order to confirm them as risk factors and to determine the specific cumulative risk fraction for each one.