The importance of neutrophil-to-lymphocyte ratio before and after radiation in breast cancer patients

Breast cancer is a common malignancy that affects the health of women worldwide. One in eight women are diagnosed with breast cancer in their lifetime^[1]. Also, 5%–7% of women are diagnosed before the age of 40, and the highest frequency is found in the age group 25–39 years^[2,3,4,5]. With the rapid advancement of early diagnosis and treatment in breast cancer, more than four-fifths of patients are now successfully treated^[4] and the mortality has recently declined in young women^[6].

Biomarkers such as neutrophils, lymphocytes, neutrophil-to-lymphocyte ratio (NLR), mean platelet volume, red cell distribution width, circulating tumor cells, and gamma-glutamyl transferase have been proposed as potential prognostic factors for cancer^{[7,8,9,10,11]}.

There is accumulating evidence for the association of NLR with survival of patients with many kinds of cancers, including breast cancer^{[12,13,14,15,16,17,18,19,20]}.

However, the published results are inconsistent. Some studies reported that NLR was significantly associated with shorter disease-free survival (DFS) and overall survival (OS) in breast cancer patients^[21,22,23], while others showed that NLR could not be considered as an independent prognostic factor for breast cancer^[24,25,26].

The challenge that we are confronted with is how to recognize the cancer-related systemic inflammation. Several studies identified some potential parameters in blood, including NLR, derived NLR (dNLR), lymphocyte–monocyte ratio (LMR), platelet–lymphocyte ratio (PLR), elevated C-reactive protein (CRP), and low albumin levels^[8,27,28].

Presence of high NLR has been found to be correlated with worse outcomes in many malignancies such as colorectal cancer, head and neck squamous cell carcinoma, soft tissue sarcoma, biliary tract cancers, ovarian cancer, gastrointestinal cancer, and breast cancer^{[29,30,31,32,33,34,35,36]}.

Neutrophils represent approximately 50%–70% of all white blood cells. They are indicators of the inflammation microenvironment state of the body, which is an important feature of various carcinomas^[37,38]. Lymphocytes are the main components of antitumor immunity. Patients with relative lymphopenia might have abnormal immune function and reduced antitumor ability, which increases the potential for cancer progression and worse outcome^[39]. NLR, the more intuitive indicator, might be a good reflection of tumor burden and immune status.

Neutrophils promote tumor progression by releasing factors that remodel the extracellular matrix in the tumor microenvironment and act on tumor cells to enhance proliferation and invasion^[40]. Tumor-associated neutrophils (TANs) are also involved in the antitumor immune response, and they interact with other immune cells such as CD8+ T cells^[37]. Radiation-induced lymphopenia elucidates the association between high NLR after the receipt of radiotherapy (RT) and poor survival outcome. Lymphocytes are highly radiosensitive, and in vitro studies have shown that the lethal dose required to reduce the lymphocyte counts by 50% is approximately 2 Gy^[41].

The aim of the research is to analyze the NLR report to define the prognostic report in patients with breast cancer. In patients with breast cancer after RT, If NRL levels decrease, prognostic factors improve.

The is a qualitative type of research that uses primary data. Data were collected from patients in Clinical Center University of Pristina, specifically in the oncology clinic. The data retrieval period was from October 2018 to June 2020.

The descriptive statistics of patents are presented in Table 1. The mean age of these 56 patients was 53.42 years with a standard deviation of 10.5 years. The oldest patient was 75 years old, while the youngest patient was 32 years old. Patients over 40 years old dominated with 51 patients or 91.07%, while patients under the age of 40 are only five patients or 8.93%.

Regarding the histopathologic status, ductal carcinoma was dominant with 31 patients or 55.36%, while non-ductal carcinoma was present in 25 patients or 44.64%. Regarding the grade assessment, grade II form dominated with 53.57%. In addition, histopathologic parameters^[42] showed that patients in the study were positive for resection (R1), vascular (V1), and lymphovascular (L1) involvement, with percentages of 17.9%, 16.1%, and 17.9%, respectively.

Regarding the status of the lymph nodes, 35 patients, or 62.5% of the total number of patients in the study, were found to have positive lymph nodes. The treatment types administered to patients in the study were as follows: postoperative chemotherapy in 64.29% of cases, hormone therapy in 7.14%, and neoadjuvant chemotherapy in 28.57%.

As for comorbidities, we have an interesting situation with a higher prevalence of hypertension classified as mild–moderate with 140/90 mmHg on average, with 29 patients or 51.79%, while with there were five patients or 8.93% with diabetes and both diabetes and hypertension were together present in 10 patients or 17.86%.

Regarding staging, one-fourth of the patients were in stage IIIA. Regarding chemotherapy treatment, the form with eight cycles with a 4AC + 4T scheme dominated in 39 patients or 69.64%. Finally, in Table 1 presents different RT treatment schemes. The most common is 25 fractions of 2 Gy per day, totaling 50 Gy, used by 29 patients (51.79%). Another scheme includes 28 fractions (25 + 3 boost) with a total of 56 Gy. The final scheme consists of 30 fractions (25 + 5 boost), totaling 60 Gy, followed by 7 patients (12.50%).In general, lymphopenia was observed in 61.3% of patients treated with RT, out of a total of 56 cases. However, a specific study focusing on each individual organ at risk was not the subject of this research.

All patients included in the study did not have metastases to other organs, except that patients with breast cancer had positive axillary lymph nodes, depending on the stage of the disease.

For all patients, the hematological examination was done (lymphocyte- LYM, neutrophil- NEU, leukocyte- WBC, erythrocyte- RBC, hemoglobin- HGB, hematocrit- HCT, mean corpuscular volume- MCV, mean corpuscular hemoglobin- MCH, monocytes- MON, thrombocyte- PLT) on the first day and on the last day of treatment. In patients with breast cancer, the average number of days of RT was 26 days in total.

The Kaplan–Meier analysis method was employed in this study to determine the OS of treated breast cancer patients. Based on the output of this method, the theoretical model for calculating the survival of patients over time was found.

The 5-year survival metrics for breast cancer in the country provided valuable insights into treatment efficacy and patient outcomes. Analysis of OS, DFS, and progression-free survival (PFS) rates revealed a strong treatment response, while also identifying areas for potential improvement. The 5-year OS rate of 81% reflected effective therapeutic strategies and early detection, but it was slightly below the rates observed in high-income countries, where the OS rates ranged from 85% to 90%. Much more in detail are present in Figure 1. This disparity suggested a need for enhancement in health-care infrastructure, particularly regarding access to care and early detection.

Figure 1:

The overall survival of treated patients by years.

The DFS rate of 87% was promising, indicating that many patients remained free of cancer recurrence. This rate was comparable to or slightly lower than those in developed countries with advanced screening and personalized treatment strategies, suggesting that improvements in post-treatment care and patient adherence to therapies are needed. The PFS rate of 88% indicated that most patients maintained a stable disease state, consistent with international figures. The comparison between DFS and PFS, with PFS being slightly higher, aligned with global trends and underscored the importance of ongoing treatment innovations. Overall, while the data demonstrated strong outcomes, they also highlighted the need for continued research and improvements in personalized medicine, patient monitoring, and access to advanced treatments to bridge the gap with countries reporting higher survival rates.

Regarding comparison of the pre- and post-treatment values, Figure 2 illustrates the percentages of lymphocytes and neutrophils before and after treatment. It is easily observed that the percentage values of lymphocytes after treatment are lower than those before treatment. Conversely, regarding the percentage of neutrophils, the opposite is true: the percentage of neutrophils after treatment is elevated.

Figure 2:

Percentage of lymphocyte and neutrophil values before and after treatment.

In Figure 2, the red circle indicates the mean value, the box indicates the 50% range, the vertical red line indicates the 90% range, the horizontal black line within the box indicates the median, and the extreme black lines outside the box indicate the minimum and maximum values.

To compare the NLR of patients before and after treatment with RT, we employed a two-tailed test method as a statistical approach. This method is commonly used to determine if there is a significant difference between two sets of data. In our case, the two sets of data are the NLR values of specific patients before and after treatment.

After performing the statistical analysis, were obtained a p-value of 0.002 for the NLR of patients. This indicates that the medication, in this case, RT, had an impact on the NLR parameter in patients.

After calculating the values of NLR before and after treatment in RT and grouping them according to the stage of the disease, grade, and number of treatment fractions, we conclude that generally, the percentage of NLR has increased after treatment compared to before treatment. More details are presented in Table 2. From the first part of this table, it is noticed that only stage III has shown lower values of NLR after treatment. All other stages show the opposite; NLR values have increased after treatment. NLRs after treatment grouped by grade show a similar trend of NLR increase after treatment, especially grade II shows a pronounced increase, followed by grade I and finally a slight increase in grade III. The highest percentage for the R1 parameter was observed in Stage IIIC, where the pre-treatment and post-treatment NLRs were 1.9 and 2.25, respectively. Meanwhile, in Stage IIIA, the highest percentages were noted for the V1 and L1 parameters, with pre-treatment and post-treatment NLRs of 2.01 and 3.03, respectively.

The number of RT fractions correlates with elevated NLR values after treatment. The highest increase was observed in patients treated with 28 fractions, followed by those receiving 25 fractions. A positive trend was also noted with 30 fractions.

The hypothesis that NLR can serve as a significant prognostic parameter for patients treated with RT is supported by its ability to reflect systemic inflammation, predict treatment response, and provide stage-specific insights. The observed increase in NLR after treatment in most cases, alongside its correlation with disease stage and treatment fractions, suggests that NLR could be a reliable marker for assessing future health outcomes. Given its simplicity, cost-effectiveness, and potential to guide personalized treatment plans, NLR may be a valuable tool for improving prognosis and optimizing RT strategies. Based on this research and previous studies, it has been confirmed that there is a tendency for lymphopenia in patients treated with RT. Therefore, it is essential to be particularly attentive in monitoring their blood profile.

Similar studies should be conducted on other types of cancers treated with RT, such as head and neck cancers, gynecological cancers, lung cancers, and others. In addition, the study period for these cases should be at least 1 year. Furthermore, the modalities of treatment for each type should also be examined.

When the patients in the study are considered individually, results show that 76.79% of them have an increased NLR factor after RT, while only 23.21% have a decreased factor after treatment. Analyzing NLR of patients according to stages reveals that patients in stage III have a better prognosis of the disease because NLR after treatment shows decreased values, whereas all other stages in the study show an increasing trend of NLR after RT.

Furthermore, the study shows that NLR values increased after treatment for all groups of patients according to grades and treatment fractions.