Detection of Ovarian Cancer through Saliva using Laser Induced Breakdown Spectroscopy Method
By: Fathkiyatus Sa’adah
The ovary is a female reproductive organ in the pelvic cavity. There is one walnut-sized ovary on each side of the uterus that is connected to the fallopian tube. The ovaries produce eggs and secrete female hormones. Every month, the ovary will release one egg. If it is not fertilized, the egg will be released together with the decay of the inner lining of the uterus, and cause women to menstruate.
Tumor may develop in the ovary and may begin to metastase to other organs in the body. This malignant tumor found in the ovary is called ovarian cancer. The Indonesian Ministry of Health in 2015 stated that in Indonesia, ovarian cancer is the third malignant cancer after cervical cancer and breast cancer. Ovarian cancer is common in middle-aged women and elderly women. The most fatal cases occur in women over the age of 55 years. This disease can be controlled by reducing risk factors.
In fact, of the top ten cancer types afflicting American women in 2008, ovarian cancer had the highest death-toincidence ratio, exceeding even that of lung cancer. Its high mortality is primarily due to difficulties in diagnosing early stage disease. Although the 5 years survival rate for stage I ovarian cancer is >90%, stage I diagnoses are more often the exception than the rule. Most patients (∼75%) present with advanced stage (III/IV) tumors, for which the 5 years survival rate is a dismal 30%. This is not surprising when one considers the anatomical problem—the ovaries are a pair of tiny organs, only ∼2–4 cm in diameter, suspended on either side of the uterus and not readily accessible by pelvic examination unless significantly enlarged. By definition, a stage I tumor is confined to the ovary and is therefore unlikely to be noticed without the aid of a sensitive screening test. Unfortunately, there are currently no effective screening modalities for detecting ovarian cancer in asymptomatic individuals. Furthermore, there are no tell-tale physical signs of the disease. Typical symptoms—which include abdominal discomfort, bloating, gas, nausea, and urinary urgency—are vague and often mistaken for gastrointestinal problems. In many cases, symptoms may not even present until the tumor has reached an advanced stage. Consequently, ovarian cancer is frequently nicknamed the ‘silent killer’.
Most ovarian cancers start in the epithelium, or outer lining, of the ovary. In the early stages, there may be few or no symptoms. Symptoms may resemble those of other conditions, such as premenstrual syndrome (PMS), irritable bowel syndrome (IBS), or a temporary bladder problem. The main difference between ovarian cancer and other possible disorders is the persistence and gradual worsening of symptoms. Early symptoms of ovarian cancer may include pain in the pelvis, the lower abdomen, or the lower part of the body, back pain indigestion or heartburn, feeling full rapidly when eating, more frequent and urgent urination, pain during sexual intercourse, changes in bowel habits, such as constipation.
As the cancer progresses, there may also be nausea, weight loss, breathlessness, tiredness and loss of appetite. If an individual experiences bloating, pressure, or pain in the abdomen or pelvis that lasts for more than a few weeks they should see a doctor immediately
Women affected by ovarian cancer will have a life span of about 1.5%. Ovarian cancer is often referred to as the ‘silent killer’ because it often causes non-specific symptoms, which results in difficulties in the detection process. This is indicated that 40% of women diagnosed with ovarian cancer only have a 5-year survival rate. However, when the diagnosis at the initial stage has increased as much as 95%.
The method of examining and diagnosing early ovarian cancer patients is still a challenge for researchers and future obstetricians. The absence of clear initial clinical symptoms in cases of ovarian cancer makes it difficult to detect it early. As a result 65-75% of new ovarian cancer cases can be diagnosed at an advanced stage.
The existing diagnostic method is by examining the vagina covering the body, rectum and pelvic cavity through the vagina to detect mass or hyperplasia (abnormal cell proliferation) in the ovary. However, there is difficulty in reaching the uterine area directly. The blood protein test (CA-125) which is an early marker of the presence of tumors, is still felt to be insufficiently sensitive to ovarian cancer screening tests. Another method developed was multiplexing tests using DNA barcodes. In addition, there are also those who use aggregate. However, with this test, ovarian cancer is difficult to detect and the method is difficult to apply.
Recently, laser technology has found a new breakthrough for early detection of ovarian cancer through patient’s saliva by using Laser Induced Breakdown Spectroscopy (LIBS). Laser induced breakdown spectroscopy is a powerful tool for identification of elements in a specimen. Because of its great sensitivity, its simplicity, and its specificity, LIBS has been used to detect chemical agents and pollutants.
LIBS is an analysis technique using laser pulses that are quite intense to identify the mineral content in the sample. The patient’s saliva will be taken and fired with a laser that will produce a spectrum. From the spectrum produced will be identified the mineral content in the patient’s saliva. The difference in mineral content between saliva of healthy people with saliva of patients affected by ovarian cancer is what will be identified further.
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