Introduction:
One can only imagine the destruction and pain caused by the killer disease, cancer. Every year, millions of people worldwide are diagnosed with cancer, and 20% of the population is at risk of developing it. More than 100 types of cancers have been identified so far that can occur in any part of the body. Unfortunately, researchers are yet to find out the cause behind cancer occurrence. Although some cancers are aggressive, they can be treated if detected early. This article describes the causes, symptoms, diagnosis, and treatment of a type of cancer called metastatic adenocarcinoma.
What Is Metastatic Adenocarcinoma?
Understanding the term “metastatic adenocarcinoma” before diving into the details.
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Metastatic: the spread of cancer cells to other parts of the body.
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Adeno: referring to a gland.
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Carcinoma: a type of cancer originating from epithelial cells (the cells lining the inner and outer surface of the body).
By definition, metastatic adenocarcinomas are those cancers originating from cells lining the glands that have been spread to various body organs. The glands involved in metastatic adenocarcinoma secrete mucous, milk, digestive juices, and hormones. In addition, many organs, like the breast, lungs, stomach, intestines, uterus, etc., contain glands that are essential for metabolic functions. Metastatic adenocarcinomas are usually denoted as stage 4 cancers as they would have spread.
Where Does Metastatic Adenocarcinoma Occur?
Most cancers occurring in the breast, stomach, and colon are adenocarcinomas. In addition, 40% of all lung cancers account for adenocarcinoma. The initially occurring cancers are called primary adenocarcinomas. However, if they spread to distant organs, it is called metastatic adenocarcinoma. Primary adenocarcinomas commonly occur as (descending order of likeliness):
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Prostate cancer.
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Pancreatic cancer.
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Colorectal cancer.
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Esophageal cancer.
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Thyroid cancer.
Why Does Metastatic Adenocarcinoma Occur?
Some cancers tend to spread without any known cause or driving force behind them. These cancers are aggressive and have the potential to surpass the body’s immune system. Factors like the type of cancer, its aggressiveness, time of diagnosis, age of the patient, and the initial treatment modality are to be considered. Additionally, the environment around the initial site is also thought to play a role. The primary tumor may not be detected in 3% to 5% of metastatic cancers. Most cancer deaths occur due to distant metastasis.
How Does Adenocarcinoma Become Metastatic?
The routes of spread of primary adenocarcinomas include:
A. Local Invasion: Adenocarcinomas invade the nearby tissues and gradually extend their roots.
B. Through Blood Circulation: Disintegrated cancer cells from the primary tumor travel to distant sites through the bloodstream.
C. Through Lymph Network: At first, cancer cells reach nearby lymph nodes. Commonly they follow a regular pattern of invasion along the course of the lymphatic network.
Where Are Adenocarcinomas Likely to Spread?
The table above mentions the common sites involved in the metastasis of adenocarcinomas. However, some of them are known to spread to the skin, muscles, and CSF (cerebrospinal fluid). Spreading to the CSF is called leptomeningeal metastasis, where cancer cells circulate in the CSF (a clear fluid surrounding the brain and spinal cord).
What Are the Signs and Symptoms of Metastatic Adenocarcinoma?
The general effects of primary adenocarcinoma on the body include:
1. Fatigue, general weakness, and malaise.
2. Unexplained weight loss.
3. Loss of appetite.
4. Presence of a lump.
5. Fever and night sweats.
6. Digestive problems.
Signs and Symptoms After Metastasis Depending on the Site:
A. Bone Metastasis:
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Bone pain.
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Weak and brittle bones.
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Easy fracture of the bones (pathologic fracture).
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Changes in calcium levels in the body.
B. Liver Metastasis:
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Abdominal swelling and pain.
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Nausea and vomiting.
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Jaundice (skin and mucous membranes turn yellow).
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Itching of skin.
C. Lung and Pleural Metastasis:
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Difficulty breathing.
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Tightness in the chest.
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Chest pain.
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Cough.
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Blood while coughing.
D. Brain Metastasis:
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Headaches.
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Changes in speech, vision, hearing, etc.
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Seizures and tremors.
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Weakness and numbness.
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Loss of body balance.
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Loss of consciousness.
E. Adrenal Metastasis:
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Asymptomatic except for back pain.
F. Peritoneal Metastasis:
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A buildup of fluid in the abdomen (ascites).
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Ascites can cause pain and difficulty breathing.
How Is Metastatic Adenocarcinoma Diagnosed?
Confirming the diagnosis of metastatic adenocarcinoma becomes a challenge, especially if the primary tumor is not detected. Commonly recommended diagnostic tools include:
1. Clinical Examination: The doctor will physically examine the patient and ask for their medical and personal histories.
2. Laboratory Tests: Blood samples are collected to assess changes in the blood count, tumor markers (substances produced by cancer cells), liver function test (LFT), serum calcium levels, etc.
3. Imaging: Advanced techniques like CT (computed tomography), MRI (magnetic resonance imaging), PET (positron emission tomography), ultrasound, and bone scans are helpful to visualize the extent of metastasis in the body. Some of these techniques produce 3D (3-dimensional) images of the suspected region.
4. Biopsy: A tissue sample is removed from the suspected site and studied under the microscope. This is useful to assess the adenocarcinoma's primary site and confirm the diagnosis.
What Is the Treatment for Metastatic Adenocarcinoma?
There is no cure for metastatic adenocarcinoma. However, most treatment modalities aim to reduce morbidity and mortality. Getting rid of the tumor, controlling its growth, and preserving the health of vital structures are essential. General treatment modalities include:
A. Surgery: Localized surgery is the first line of treatment in the initial stages. Even after metastasis, surgery is carried out to reduce the size of the tumor. Surgery also includes ablative therapies, where the blood vessels supplying the tumor are cut off.
B. Radiotherapy: High-energy radiation is used to shrink the size of the tumor. High doses of radiation kill cancer cells by damaging their DNA (deoxyribonucleic acid).
C. Chemotherapy: Medications called cytotoxic (cell-killing) drugs interfere with the cancer cell cycle. Chemotherapeutic drugs can be given orally or systemically (through a vein).
D. Targeted Therapy: Utilizes medications that jeopardize specific pathways in cancer growth. They only target cancer cells and have fewer side effects than other therapies. They are also known to improve the survival rate and quality of life after the treatment.
E. Immunotherapy: Drugs that boost the body’s natural immune system or help them fight against cancer cells. However, not all the cases respond positively to immunotherapy.
F. Hormonal Therapy: Hormone inhibiting drugs can be used in cancers that are driven by hormones. For example, 70% of breast cancers are estrogen-powered.
Conclusion:
Metastatic adenocarcinomas are those cancers originating from cells lining the glands that have been spread to various distant body organs. Primary adenocarcinomas commonly occur in the breasts, stomach, colo-rectal region, lungs, prostate, etc. The primary tumors from these regions spread to the liver, lungs, brain, bones, and sometimes the peritoneum. Metastasis usually occurs in stage 4, and treatment modalities are only helpful in increasing the quality of life. Diagnosing at earlier stages will give the best chance for survival.