# Evaluation of digit ratio (2D:4D) in breast cancer patients

## TL;DR

This study examines the 2D:4D finger ratio in breast cancer patients to explore its link with prenatal hormonal exposure and cancer subtypes.

## Contribution

The study is the first to evaluate 2D:4D ratio differences among pathological subgroups of breast cancer.

## Key findings

- The right hand 2D:4D ratio was significantly lower in the Luminal A breast cancer subgroup.
- No significant age differences were found between breast cancer subgroups and the control group.
- The 2D:4D ratio may be associated with breast cancer, particularly in the hormone receptor-positive Luminal A group.

## Abstract

Breast cancer is a hormone-dependent cancer. Hormonal exposure begins in the intrauterine period and continues in later years of life. 2D:4D ratio is accepted as an indicator of this exposure. The aim of this study was to investigate whether there is a difference in 2D:4D ratio between pathological subgroups of breast cancer and healthy control group. In this study, 204 participants, 154 breast cancer patients and 50 healthy control volunteers with similar age distribution, were included. Both hands of all participants were scanned using a digital scanner. The second and fourth finger lengths were measured using a digital measuring ruler with an accuracy of 0.05 mm. The 2D:4D ratio was calculated as the length of the second finger divided by the length of the fourth finger. A total of 204 patients (55 triple negative, 52 luminal B, 33 luminal A, 14 HER2-overexpessing and 50 healthy control volunteers) were subjected to finger scanning. There was no statistically significant difference in mean age between the groups. The right hand 2D:4D ratio was significantly lower in the Luminal A group compared to the other groups (p < 0.048). Although prenatal hormonal exposure is accepted as a risk factor for breast cancer, no study has evaluated patients in pathological subgroups. The 2D:4D ratio may be associated with breast cancer especially in the luminal A group in which hormone receptors are strongly positive and which has a better prognosis compared to the other groups.