The spread of cancer to the brain is one of the most feared complications of cancer therapy and also comes with significant mortality and morbidity. This phenomenon occurs when cancer cells travel through the bloodstream or the lymph system from the original tumour and metastasize to the brain. This is known as metastatic cancer. For example, breast cancer that has spread to the brain would be referred to as metastatic cancer and not primary cancer.
According to Globocan 2018 report issued by International Association of Cancer Registries (IARC) — a World Health Organization (WHO) associate — over 28,000 new brain tumour cases are reported annually in India and around 24,000 patients lose their lives battling such deadly and cancerous tumours.
Most people ignore the initial symptoms of this disease, such as headaches, vomiting, seizures etc. As the exact location of the tumour is often wrongly determined, this condition often leads to misdiagnosis that can even result in the death of the patient. However, such trends are gradually declining thanks to the improved treatment of such deadly tumours, improving survival rates.
The following symptoms can be caused by brain metastasis, but many patients may experience additional complications caused by the original tumour and its related manifestation.
Increased pressures within the skull:
In most cases, the symptoms are caused by the expansion of lesions and increased ICP (intracranial pressure). The most common symptoms of ICP are headaches, vomiting and disturbances in consciousness.
Headache: Headache is the initial symptom in more than half of the cases of brain tumour and this is faced by most of the patients at some point in their life.
Vomiting: This is an occasional accompaniment with headaches. It is far more common in children. In children, this can be dramatic and forceful, and may be labelled as projectile in nature.
Seizures: It is an uncontrolled electrical disturbance in the brain. It causes changes in the mental behaviour, movements and level of consciousness. These are almost associated with 35% cases of brain tumours.
Specific neurological symptoms: Whereas headaches that alter mental status and seizures may be seen with tumours that occur in any part of the brain, some symptoms are associated with the tumours that occur in a specific location. These symptoms affect the side of the body opposite from the side where the tumour resides and may include different modalities of sensation such as tingling and motor changes.
Spread of systemic malignancy
Virtually any systemic malignancy can metastasize to the brain, but there are some which have greater tendency to do so. Melanoma, a type of skin cancer, is a case in point. Other cancerous tumours of the skin, breast, kidney and the colon can also metastasize to the brain. Some differences are seen in the types of primary malignancies responsible for metastasis of the brain in both the genders. In males, lung cancer is the most common source of brain metastasis whereas breast cancer is the most common source in females.
Brain metastasis can be diagnosed with the following tests:
CT/CAT scan: It can be done with or without injecting intravenous contrast and includes different views of the brain. CT scans are utilized as initial diagnostic tests.
Magnetic resonance imaging (MRI): It makes a clear picture of the brain using powerful magnets and radio waves. With the addition of intravenous contrast agents, this has become the gold standard in testing and provides information about the location, size, characteristics and pressure effects of the tumour.
PET Scan: Positron emission tomography (PET) scans can detect cancer, reveal the stage of cancer, show whether the cancer has spread, help doctors decide on the most appropriate cancer treatment, and give doctors an indication of the effectiveness of ongoing chemotherapy. They are also useful in finding out how effective the current treatment is. The biggest advantage of a PET scan, compared to an MRI scan or X-ray, is that it can reveal how a part of the patient’s body is functioning, rather than just how it looks. Medical researchers find this aspect of PET scans particularly useful. A CT or MRI scan can assess the size and shape of body organs and tissue, but cannot assess its function like the PET scan does. In other words, MRI or CT scans tell you what an organ looks like, while a PET scan can tell you how it is working.
Tissue diagnosis is crucial and may have already occurred if the patient has a previously known malignancy. It may be obtained by biopsy or removal at the site of the primary cancer. Besides this, a biopsy of the metastatic brain tumour is performed if the size is large and it is causing significant pressure effects. The tumour may be removed entirely to relieve the pressure while providing adequate tissue for diagnosis.
Once a clear diagnosis of the tumour is obtained and the staging of the systemic cancer is completed and the patient’s medical condition stabilized, a multidisciplinary team of physicians will try to treat the tumour within the brain with the best possible treatment methods.
Treatment varies with the size and type of tumor, the primary site of malignancy — whether it is local or at multiple spots in the body, the general health of the individual and the presence of other medical problems. The goals of the treatment involve improving body functioning, controlling the cancer and its satellite tumours within the brain.
Cyberknife is performed in a non-invasive manner on an outpatient basis. The therapy aims to pinpoint the exact location of the tumor in real-time using 3-D imaging techniques and to ablate the tumour without any cut marks. Its outcomes are superior to those of traditional methods of treatment. It also provides more comfort to the patient as it can be carried out in 1 to 5 sessions 30 minutes each.
The main advantage of cyberknife radiation therapy is that it directly alters individual deposits inside the brain without affecting brain functioning. Separately, Whole Brain Reserve Therapy (WBRT) is reserved for those unfortunate patients who have too many deposits to be treated with cyberknife or who prefer multiple cyberknife treatments. In fact, for the treatment of metastasis in cases such as melanoma, radiation therapy (cyberknife) may be the only option.
The author is Director – Cyberknife, Artemis Hospital, Gurugram.