The Role of Interleukin-7 Serum Level as Biological Marker in Breast Cancer
Condition: Breast Cancer Invasive
MeSH terms: Breast Neoplasms
Study type: Observational

Summary: 
      The aim of this study has been to explore whether there is any elevation of Interleukin-7
      serum level in the early invasive breast cancer (EIBC) patients in comparison with healthy
      controls. In addition the correlation between the Interleukin-7 serum level and
      histopathological characteristics of the tumor, has been evaluated.

      We have hypothesized that Interleukin-7 serum level is elevated in the patients diagnosed
      with early invasive BC in comparison with healthy control group, and positively correlates
      with the tumor size, poor cell differentiation, lymphovascular and perineural invasion,
      negative hormone receptors' status, axillary lymph node metastasis, and the high Ki-67
      proliferation index. In addition, no difference in the Interleukin-7 serum level exists
      between the patients recruited in Croatia and Kosovo, respectively.

      This cross-sectional, observational, and analytical study has included 213 consecutive
      patients with EIBC (113 from Croatia and 100 from Kosovo) and 62 healthy participants as the
      control group (30 from Croatia and 32 from Kosovo). Blood samples have been taken from
      patients confirmed with breast cancer (BC) by biopsy, prior to surgical intervention and
      other oncological treatments, as well as from healthy participants. Interleukin-7 serum level
      has been measured, using "Sandwich" ELISA Immunoenzyme test. In addition, after the surgical
      intervention, the histopathological specimen examinations and the immunohistochemistry have
      been performed and analyzed. The differences of the distribution of the numerical variables
      have been analyzed with Mann-Whitney U test and Kruskal-Wallis ANOVA test. Correlations have
      been tested with Pearson coefficients. P value <0.05 has been accepted as statistically
      significant.
    

Detailed description: 
      This cross-sectional, observational, and analytical study has been undertaken in the Clinic
      of Oncology, University Hospital Center Zagreb, Croatia, and the Department of Thoracic
      Surgery in the University Clinical Center of Kosovo in Prishtina, Kosovo, from June 2018
      until December 2019. In order to determine the Interleukin-7 serum level, blood samples (10
      ml venous blood) have been taken from 213 EIBC patients, from which 100 from Kosovo
      University Hospital and 113 from Croatian University Hospital, prior to surgery and other
      oncological treatments, such as chemotherapy, radiotherapy, endocrine therapy or target
      therapy. On the other hand, the blood samples (10 ml venous blood) have been taken also from
      other 62 healthy participants, which compose the control group, from whom 32 from Kosovo and
      the other 30 from Croatia. Blood samples categorized in tubes have been identifiable only by
      the numbers attributed to participants, and have been stored frozen in temperatures of -20˚C,
      in order to conduct the analysis later.

      Patients have been selected as consecutive among women, aged between 20 - 70 who are
      confirmed to BC, by biopsy, operable and without distant metastases. Patients with
      pathological conditions, such as acute and/or chronic inflammatory diseases, rheumatoid
      disease and other malignancies occurring simultaneously, patients receiving immune modulatory
      therapy, patients previously treated by surgery, chemotherapy, radiotherapy, target therapy
      or endocrine therapy, patients with dementia or any other psychological disorders unable to
      willingly participate in the study, have been excluded. The control group has been composed
      by women, aged between 20 - 70, without breast tumors, confirmed by ultrasound or mammography
      in the last three months or any other confirmed malignancies, without any acute or chronic
      inflammatory disease as well as no receiving immune modulatory therapy.

      In this study, the Interleukin-7 serum level has been measured, using "Sandwich" ELISA
      Immunoenzyme test, human Interleukin-7 antibody, and Platinum ELISA using research tools from
      eBioscience Inc., located in San Diego, CA USA. After the surgery (partial or modified
      radical mastectomy) with or without axillary lymph node dissection or sentinel lymph node
      biopsy (SLNB), the histopathological specimen examinations have been performed according to
      routine practice, and the histopathological and immunohistochemistry features have been
      evaluated. Cancer staging has been conducted according to tumor node metastasis
      (TNM)-classification, by the American Joint Committee on Cancer Classification (AJCC). The
      patients have been classified in accordance to their pathological characteristics, including
      tumor size, histological types, histological grade, LVI and PNI, metastatic lymph nodes,
      molecular markers such as; ER, PR, amplification of Her-2/neu, Ki-67 proliferation index,
      molecular surrogate subtypes according to the St Gallen consensus criteria. The data on age
      and menopausal status have been also obtained from the patients.

      Interleukin-7 serum level has been initially determined in all the study participants,
      including patients and the control group. Then it has been evaluated if there has been any
      difference of Interleukin-7 serum level between EIBC patients and control group. After that,
      appropriate analyzes have been done to see if there is any correlation between Interleukin-7
      serum level of the patients and histopathological characteristics of the tumor, as well as
      age and menopausal status. In addition, the potential difference of Interleukin-7 serum level
      between patients coming from Croatia and Kosovo has been evaluated.

      After checking for normality of distribution, numerical variables have been presented as
      median and interquartile range. The differences of the distribution of the numerical
      variables have been analyzed with Mann-Whitney U test and Kruskal-Wallis ANOVA test.
      Associations between numerical variables have been analyzed as Spearman rank correlation
      coefficient. Analyses have been performed with statistical software SPSS-22.0. The diagnostic
      accuracy and the optimal cut point value for Interleukin-7 level between two groups have been
      obtained based on the value of the area under the ROC curve.
    

Observational model: Other
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        In order to determine the Interleukin-7 serum level, blood samples (10 ml venous blood)
        have been taken from 213 EIBC patients, from which 100 from Kosovo University Hospital and
        113 from Croatian University Hospital, prior to surgery and other oncological treatments,
        such as chemotherapy, radiotherapy, endocrine therapy or target therapy. On the other hand,
        the blood samples (10 ml venous blood) have been taken also from other 62 healthy
        participants, which compose the control group, from whom 32 from Kosovo and the other 30
        from Croatia. Blood samples categorized in tubes have been identifiable only by the numbers
        attributed to participants, and have been stored frozen in temperatures of -20˚C, in order
        to conduct the analysis later.

        Patients have been selected as consecutive among women, aged between 20 - 70. Also, the
        control group has been composed by women, aged between 20 - 70.
      
Keywords: Breast cancer, interleukins, interleukin-7, biomarker