# Computer-Assisted Screening for Cervical Cancer Using Digital Image Processing of Pap smear Images
## 1 Introduction  
Cancer is the uncontrolled growth of abnormal cells in the body. Rather than responding appropriately to the signals that control normal cell behavior, cancer cells grow and divide in an uncontrolled manner, invading normal tissues and organs and eventually spreading throughout the body [1]. Cervical cancer is cancer arising from the cervix. The most important risk factor for cervical cancer is infection with human papillomavirus (HPV). The goal of cervical screening is to identify and remove significant precancerous lesions in addition to preventing mortality from invasive cancer. Cervical cancer is the fourth most frequent cancer in women, with an estimated 570,000 new cases in 2018, representing 6.6% of all female cancers. Approximately 90% of deaths from cervical cancer occur in low- and middle-income countries. Precancerous changes in the cervix usually don't cause any signs or symptoms [2]. Symptoms of cervical cancer include irregular interminstrual (between periods) or abnormal vaginal bleeding after sexual intercourse, back, leg or pelvic pain, fatigue, weightloss, loss of appetite, vaginal discomfort or odorous discharge, and a single swollen leg. More severe symptoms may arise at advanced stages [3]. Cervical cancer can be prevented by regular screening tests if precancerous changes are detected and treated effectively before cancer develops. Cervical cancer typically develops from precancerous changes over 10 to 20 years. The only way to know if there are abnormal cells in the cervix, which may develop into cervical cancer, is to have a cervical screening test. Screening is testing of all women at risk of cervical cancer, most of whom will be without symptoms. A Pap test is commonly used to screen for cervical cancer. A Pap smear is a simple, quick, and essentially painless screening test (procedure) for cancer or precancer of the uterine cervix. Cervical cancer testing should start at age 21. Women under age 21 should not be tested. Women between the ages of 21 and 65 should have a Pap test done every 3 years. About 80 percent of deaths from cervical cancer occur in developing countries due to the lack of screening programs [4]. The regular Pap test system reduces the incidence rate of cervical cancer. The visual examination of the Pap smears is time-consuming, very demanding, tedious, and expensive in terms of labor requirements. The cytotechnologists are laboratory professionals who study cells and cellular anomalies who go through specialized training, typically of about one year. The Pap test or smear starts with the pelvic exam. In this exam, cell samples are collected from the cervix and stained on a glass slide. The collected cells are visually examined under a microscope to classify each cell. The shape, size, texture, and nucleus to cytoplasm ratio are the important features to classify the cervical cells into normal and abnormal epithelial cells [5]. Literature reviews that are related to previous research studies about cervical cancer cells' segmentation and classification are described as follows: [PERSON] et al. proposed Pap smear images classification for cervical cancer detection using a support vector machine (SVM) classifier and got an accuracy of 92.961% [6]. In another study, [PERSON] et al. presented an approach to segment cells cluster using intensity variation. But most of the real Pap smear images were poor contrast, and sometimes intensity variation was invisible in overlapping conditions [7]. [PERSON] et al. also developed the method of overlapping cell separation by integrating edge detection and pseudo-color algorithm. The seed-based region growing method was used to detect the boundary of cells, and cell components (nucleus, cytoplasm, and background) were grouped according to color techniques [8]. Most research studies focus on the nuclei segmentation in a single [9] or overlapping cells [10], and other researchers focus on the nuclei segmentation in both single and overlapping cells [11].