Biology, Medicine, & Natural Product Chemistry ISSN 2089-6514 (paper) Volume 8, Number 1, 2019 | Pages: 11-15 | DOI: 10.14421/biomedich.2019.81.11-15 ISSN 2540-9328 (online) Mathematical Model of Cervical Cancer Treatment Using Chemotherapy Drug Murtono1,*, Meksianis Zadrak Ndii2, Sugiyanto3 1Department of Physics Education; 3Department of Mathematics, Universitas Islam Negeri Sunan Kalijaga, 55281, Yogyakarta, Indonesia. 2Department of Mathematics, Faculty of Science and Engineering, University of Nusa Cendana, Kupang-NTT, Indonesia. Author correspondency*: hasnamur@yahoo.co.id Abstract Cervical cancer is a malignant disease that causes problems in women's health, espe cially in developing countries such as Indonesia. Cervical cancer cells will develop quickly, uncontrollably, and will continue to divide and then infiltrate the surrounding t issue and continue to spread to connective tissue, blood, and attack important organs and spinal nerves. The aim of the research is to study the mathematical model of cervical cancer by chemotherapy treatment. The results of this study are that cervical cancer treatment using chemotherapy is effective enough to kill abnormal cells such as infected cells, pre-cancerous cells and cancer cells, although there are side effects, namely the killing of normal cells due to chemotherapy drugs. Keywords: Cervical cancer; infected cells; infected cells; cancer cells; chemotherapy INTRODUCTION Cervical cancer is an excessive and uncontrolled cell growth around the cervix (Walboomers et. al., 1999). Cervical cancer originated from cells in the cervix (Naganawa et al., 2005). Most cervical cancers begin in the transformation zone which is a shift from squamous cell type to cylindrical cell type. These cells do not directly turn into cervical cancer. Normal cervical cells due to the influence of carcinogenic substances can develop gradually into pre-cancerous cells and then become cancer cells (Sari et al., 2016). The main trigger for the emergence of cervical cancer is infection of several types of high-risk Human Papilloma Virus (HPV) which causes proliferation of the epidermal surface and cervical mucosa (Bosch, 1995). The types of HPV that are very common in cases of cervical cancer are types 16 and 18, which is more than 70% of all cervical cancers reported. The results of a study of 1,000 samples from 22 countries proved the presence of HPV infection in 99.7% of cervical cancer cases (Wuryanti et. al., 2015). Cervical cancer is the second most common type of cancer in women worldwide to breast cancer (Boice et. al., 2002). Chemotherapy is a kind of cancer treatment that uses drugs to destroy cancer cells. Chemotherapy works by stopping or slowing the growth of cancer cells, which grow and divide rapidly. Chemotherapy can also harm healthy cells that divide rapidly, such as the lines of the mouth and intestines or cells that affect growth. Damage to healthy cells can cause side effects. Often, side effects will be disappear after chemotherapy is complete (Rose et. al., 1999). Reduction of the mass of cervical cancer can be used as used to measure the effectiveness of treatment because chemotherapy can cause shrinkage of the mass of cervical cancer. Cancer mass has an important role to detect the prognosis of a cervical cancer. FORMULATION OF MODEL This model developed frpm the past research (Asih, et. al., 2015) about the development of cervical cancer and Pillis et al. (2007) about the model of treating cancer in general with chemotherapy. Figure 1. Cervical Cancer Treatment Diagram by Chemotherapy. https://doi.org/10.14421/biomedich.2019.81.11-15 12 Biology, Medicine, & Natural Product Chemistry 8 (1), 2019: 11-15 Table 1. Subpopulations, Parameters and units. Symbol Symbol Explanation Unit Unit S(t) Normal cell density cell/mm2 I(t) Infected cell density cell/mm2 P(t) Pre-cancerous cell density cell/mm2 C(t) Cancer cell density cell/mm2 V(t) Virus density virus/mm2 M(t) Concentration of chemotherapy drugs mg/m2 r Growth rate of normal cell 1/day N Homeostatic carrying capacity cell/mm3  The rate of infection 1/(day.virus) 1a The rate of proliferation of infected cells 1/day 1d The rate of infected cell apoptosis 1/day  The rate of progression, from infection to pre-cancer 1/day 2a The rate of proliferation of pre- cancerous cell 1/day 2d The rate of pre-cancerous cell apoptosis 1/day  The maximum invasion rate, from precancerous to cancer 1/day K Half-saturation consentration cell/mm3 3a Cancer cell proliferation rate 1/day 3d Summing the rate of apoptosis and the rate of cancer cell metastasis 1/day n The average number of viruses produced by an infected cell constant 4d The rate of virus death 1/day Sk Fractional susceptible cells kill by chemotherapy 1/day Ik Fractional infected cells kill by chemotherapy 1/day Pk Fractional pre-cancerous cells kill by chemotherapy 1/day Ck Fractional cancer cells kill by chemotherapy 1/day  The rate of chemotherapy drug decay 1/day Mv The rate of chemotherapy drug intake mg/m2.day The dynamics of changes in cervical cells from normal cells to cancer cells are given in the following system of differential equations: 1 S dS S I rS SV k MS dt N           (1a) 1 1 I dI SV a I d I I k MI dt       (1b) 1 1 4 dV n d I d V dt   (1c) 2 2 2 2 2 P dP P I a P d P k MP dt K P        (1d) 2 3 32 2 C dC P a C d C k MC dt K P       (1e) M dM M v dt    (1f) Let 1 1 2 2 3 3 1 1 1 1 1 1 4 , , , , , , , , , , S I a d a b a d k d a S I N N P C N P C n n d N c d p K K K K                 By non-conventionalizing the System (1a) - (1f) to be   1 1 1 1 1 11 S dSdS rS S I S V k MS dt dt       (2a) 1 I dIdI SV aI I k MI dt dt       (2b) dV nI cV dt   (2c) 2 1 12 1 p dP P pI bP k MP dt P       (2d) 2 2 1 C dC P kC k MC dt P     (2e) M dM M v dt    (2f) By eliminating the variable index, System (2a) - (2f) which is non-professional becomes   1 S dS rS S I SV k MS dt      (3a) I dI SV aI I k MI dt      (3b) dV nI cV dt   (3c) 2 2 1 P dP P pI bP k MP dt P       (3d) 2 2 1 C dC P kC k MC dt P      (3e) M dM M v dt    (3f) Murtono et al. – Mathematical Model of Cervical Cancer Treatment … 13 EQUILIBRIUM POINT Theorem 1. Let 3 22 9 27 , 3u x xy z v x y     . The equilibrium point with chemotherapy in cervical cancer from System (3a) - (3f) is     * * * * * * 3 4 5 5 2 5 1 , , , , , , , , , ,i i EP S I P C V M p c          1 2 3i , , , where 1 0 Mv    , 2 0 n c    , 1 3 1 Sk r     , 2 4 1 0 r            , 1 2 3 5 2 4 Ia k          , 5 1 , P p x k b        51 1 1 , .P P P pk b y z k b k b           Proof. From equation (3f) is obtained 1 0 MvM      . (4) From equation (3c) is obtained 2 nI V I c   , (5) where 2 0 n c    . If equation (4) and equation (5) are substituted into equation (3a), then we obtain 3 4S I   , (6) where 13 1 Sk r     and 24 1 r           . If equations (4), (5) and (6) are substituted in equation (3b), they are obtained 0I  or 1 2 3 5 2 4 Ia kI             , (7) where 1 2 35 2 4 Ia k          . For 𝐼 = 0 impossible, because the virus is the cause of cervical cancer, so it was chosen 𝐼 = 𝜉5. If equation (4) and equation (7) are substituted into equation (1d), then they are obtained 𝑃3 + 𝑥𝑃2 + 𝑦𝑃 + 𝑧 = 0, where 5 51 1 1 1 , , .P P P P p pk b x y z k b k b k b                  The roots are 2 33 1 2 33 1 1 4 3 3 2 1 1 4 , 3 2 x p u u v u u v                 , 2 33 2 2 33 1 3 1 4 3 6 2 1 3 1 4 6 2 x i p u u v i u u v                   2 3 3 3 2 3 3 1 3 1 4 3 6 2 1 3 1 4 . 6 2 x i p u u v i u u v                 (8) If equation (4) and equation (8) are substituted into equation (3e), then they are obtained 𝐶 = 𝜃𝑝𝑖 2 (𝑘+𝑘𝐶𝜉1)(1+𝑝𝑖 2) = 𝑐𝑖, where 𝑖 = 1,2,3.■ Theorem 2. If 1 2 3 0Ia k       , 3 4 5 0    and if one 𝑝𝑖 > 0 and real, then the equilibrium point with chemotherapy or value 𝐸𝑃 exist. Proof. From Theorem 1 is obtained 𝑀 = 𝑣𝑀 𝛾 = 𝜉1 > 0. Because 𝑎 + 𝛿 + 𝑘𝐼𝜉1 − 𝑎𝜉2𝜉3 > 0, then 𝐼 = 𝑎+𝛿+𝑘𝐼𝜉1−𝑎𝜉2𝜉3 𝑎𝜉2𝜉4 = 𝜉5 > 0. Because 𝐼 = 𝜉5 > 0, then 𝑉 = 𝑛𝐼 𝑐 = 𝜉2𝐼 > 0. Because 𝜉3 + 𝜉4𝜉5 > 0, then 𝑆 = 𝜉3 + 𝜉4𝜉5 > 0. One is 𝑝𝑖 > 0, where 𝑖 = 1,2,3 and real. Value is 𝜃𝑝𝑖 2 (𝑘+𝑘𝐶𝜉1)(1+𝑝𝑖 2) = 𝑐𝑖 > 0. So, the equilibrium point with chemotherapy or value 𝐸𝑃 exist.■ STABILITY Theorem 3. Let 𝑢 = 2𝑥3 − 9𝑥𝑦 + 27𝑧, 𝑣 = 𝑥2 − 3𝑦. If −𝑘 − 𝑘𝐶𝜉1 < 0, 𝑏 − 2𝜃𝑝𝑖 (1+𝑝𝑖 2) − 𝑘𝑃𝜉1 < 0, where 𝑖 = 1,2,3, 𝑥 > 0, 𝑢 > 0, 𝑢2 = 4𝑣3, and 𝑢 < 2𝑥3, then equilibrium point 𝐸𝑃 = (𝜉3 + 𝜉4𝜉5,𝜉5,𝜉2𝜉5,𝑝𝑖, 𝑐𝑖,𝜉1) asymptotic stable. Proof. From System (3a) - (3f) the Jacobian matrix with eigenvalue is obtained 1   , 2 1Ck k    ,   3 12 2 2 1 i P i p b k p       , 14 Biology, Medicine, & Natural Product Chemistry 8 (1), 2019: 11-15 2 33 4 2 33 1 1 4 3 3 2 1 1 4 , 3 2 x u u v u u v                  2 33 5 2 33 1 3 1 4 3 6 2 1 3 1 4 6 2 x i u u v i u u v                    2 33 6 2 33 1 3 1 4 3 6 2 1 3 1 4 . 6 2 x i u u v i u u v                    Value is 𝜆1 = −𝛾 < 0. Because −𝑘 − 𝑘𝐶𝜉1 < 0, then 𝜆2 = −𝑘 − 𝑘𝐶𝜉1 < 0. Because 𝑏 − 2𝜃𝑝𝑖 (1+𝑝𝑖 2)2 − 𝑘𝑃𝜉1 < 0, then 𝜆2 = 𝑏 − 2𝜃𝑝𝑖 (1+𝑝𝑖 2)2 − 𝑘𝑃𝜉1 < 0. Because 𝑣 = 0, then 𝜆4 = − 𝑥 3 − 1 3 √𝑢 3 , 𝜆5 = − 𝑥 3 − 1 3 √ 1 2 𝑢 3 , 𝜆6 = − 𝑥 3 + 1 3 √ 1 2 𝑢 3 . Because 𝑢 > 0, then 𝜆4 < 0. Because 𝑢 < 𝑥 3, then 𝜆5 = 𝜆6 < 0. Because 𝜆1,𝜆2,𝜆3,𝜆4,𝜆5 and 𝜆6, then the equilibrium point 𝐸𝑃 asymptotic stable.■ SIMULATION In this section we will discuss numerical simulations and medical interpretations of the mathematical model of cervical cancer affected by chemotherapy. First, the parameter values used and the initial values for each variable are given first. Taking parameter values for numerical simulations is still in the form of assumptions based on the rate of growth of cancer cells in general. Sources and interpretations of parameter values can be seen in the reference. The parameter values for this case are given in Table 2. Table 2. Case Parameter Value of the Effects of Chemotherapy. Symbol Value Reference 𝑟 0.02 Asih et al. (2015) 𝛼 0.0001 Asih et al. (2015) 𝑎 0.01 Asih et al. (2015) 𝛿 0.0082 Asih et al. (2015) 𝑛 10000 Asih et al. (2015) 𝑐 50 Asih et al. (2015) 𝑝 13.44 Asih et al. (2015) 𝑏 1 Asih et al. (2015) 𝜃 2.03 Asih et al. (2015) 𝑘 1.01 Asih et al. (2015) 𝑘𝑆 0.0006 Estimation 𝑘𝐼 0.6 Pillis et al. (2007) 𝑘𝑃 0.6 Pillis et al. (2007) 𝑘𝐶 0.8 Pillis et al. (2007) 𝛾 0.9 Pillis et al. (2007) 𝑣𝑀 1 Pillis et al. (2007) Figure 2. System Simulation (3a) - (3f) with parameter values 𝑟 = 0, 𝛼 = 0.0001, 𝑎 = 0.01, 𝛿 = 0.0082, 𝑛 = 10000, 𝑐 = 50, 𝑝 = 13.44, 𝑏 = 1, 𝜃 = 2.03, 𝑘 = 1.01, 𝑘𝑆 = 0.0006, 𝑘𝐼 = 0.6, 𝑘𝑃 = 0.6, 𝑘𝐶 = 0.8, 𝛾 = 0.9, 𝛾 = 1, and initial conditions (13, 13, 13, 13, 13, 13). The dynamics due to normal cell chemotherapy drugs, infected cells, precancerous cells, cancer cells, cancer cells, and viruses declined in three days. (A) normal cells. (B) Infected cells, precancerous cells, and cancer cells. (C) Viruses. (D) Chemotherapy drug concentration. Murtono et al. – Mathematical Model of Cervical Cancer Treatment … 15 Figure 2 shows a trajectory with the influence of chemotherapy drugs, on cervical cancer patients. Normal cells in the first 3 days showed a decrease, from 13 cells/mm2 to 7,254 cells/mm2. This makes a severe effect for cervical cancer patients with this chemotherapy drug. Infected cells, precancerous cells and cancer cells drop very quickly, in the first 3 days of chemotherapy, from 13 cells/mm2 to 0.01308 cells/mm2. The initial virus rose would derease after chemotherapy. The virus in 3 days is from 13 viruses/mm2 to 0.3771 viruses/mm2. This is because, many infected cells die because of the effects of chemotherapy drugs. The chemotherapy drug on the third day still contained 1.91mg/m2. It means that chemotherapy drugs still have an effect on normal cells and other abnormal cells, including cancer cells. CONCLUSION Cervical cancer is one type of malignant cancer and is most prevalent in women compared to other cancers. Treatment of cervical cancer with chemotherapy is quite effective. Abnormal cancer cells such as infected cells, precancerous cells, and many cancer cells die from this treatment. 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