Chemotherapy [4]

Chemotherapy [4]

Chemotherapy can be administered in a variety of ways and this is largely due to the type of tumour, its progression and your overall health. Usually, this has already been studied in carefully planned clinical trials, which examined not only the efficacy of the particular drug but also its safety, tolerability, toxicity, optimal dosage, mode of administration and type of tumour for which the particular drug is best suited. Similarly, it’s also been studied how the drug spreads throughout the body, how long it circulates in the bloodstream, where it’s metabolised, how it interacts with other drugs and how it’s expelled from the body. However, despite these observations, there’s always a possibility that your tumour and your body will react differently than expected to the drug. The majority of drugs are administered systemically (intravenously, via infusion, through long-term catheters, etc.), because if administered orally there’s a chance that your gastric juices will destroy them. Oral medications (tablets, capsules), which can be taken at home are much more convenient for the patient. Therefore, new generation drugs are often taken orally. But this doesn’t influence their efficacy. Similarly, you’ll often hear excuses that patients should use the old (created earlier) drugs. The benefits of a drug aren’t dictated by the year it was invented, produced or put on the market, but rather by its suitability to treat a specific tumour, its efficacy, tolerability and safety. Oncological drugs aren’t products that can be modern or go out of style. They’re not scarves, shoes or handbags, that either are or aren’t in fashion. Therefore, the claim that Latvia uses ancient drugs is simply biased and false. Many of the drugs still used in oncology today were created a half century ago, yet they haven’t been removed from the world’s pharmacopeia (stock of medicines) and serious clinical guidelines (NCCN, ESMO) haven’t removed them from their recommendations.

Oral oncology drugs are usually covered in a protective layer which is dissolved in the stomach releasing the active ingredient. They’re available in capsule and tablet form. Sometimes this protective layer is designed in such a way that the drug is dissolved very slowly and gradually, allowing it to be used less frequently, as it works for a longer period of time. Therefore, these drugs should be swallowed whole without chewing. Some anti-nausea drugs are placed under the tongue, where they are absorbed the quickest and their efficacy isn’t affected even by vomiting, which would otherwise have expelled the drug from the stomach before it had achieved any clinical effect.

During a subcutaneous injection (injection with a hypodermic needle) the drug is administered between the skin and subcutaneous muscle. A variety of organic substances and support agents meant to alleviate or treat the effects of chemotherapy are often administered in this manner. Subcutaneous injections are safer in patients with reduced platelet counts, as they’re much less likely to cause bleeding (bruising) than intramuscular injections.

During intramuscular injections drugs are introduced through the skin into the muscle mass. Thicker needles are often used for this purpose than for subcutaneous injections and the drugs are usually stored or deposited in the muscle tissue, from which they gradually spread throughout the entire body. The absorption of the drug occurs faster after an intramuscular injection than if it’s administered orally. However, drugs that are injected intramuscularly are absorbed slower than drugs taken under the tongue, under the skin or as an IV injection. Unfortunately, most chemotherapy drugs can’t be delivered intramuscularly, because they cause irritation. Intramuscular injections are also usually avoided in patients with low platelet counts and a high risk of bleeding.

Intravenous injections are administered directly into the vein, where the drugs are quickly spread via the bloodstream. The majority of chemotherapy drugs are well-absorbed by the body, so this is the most popular method of delivering these drugs. Moreover, depending on the planned treatment and chosen drug, intravenous injections can be either short- or long-term when using a variety of support devices (disposable systems, ports, long-term catheters et al).

During intrathecal or intraventricular injections drugs are delivered via the cerebrospinal fluid (the fluid that surrounds the hollow spaces of the spinal cord and brain). In this way it’s possible to deliver the drugs to the brain, bypassing the natural blood-brain barrier (between the bloodstream and brain cells), which acts as a unique filter that would otherwise prevent the drugs from reaching their goal. For example, drugs can be administered via a spinal tap (lumbar puncture). This method of delivery can be used on its own or in combination with other delivery methods. Intrathecal injections have been used quite successfully to alleviate pain associated with chronic cancers.

Intraperitoneal chemotherapy is when a drug is administered directly through a catheter into the abdominal cavity. The patient is asked to change positions so the medication can be better absorbed by the abdominal organs. Sometimes the drug is removed after a certain time, but other times it remains in the abdomen and is slowly absorbed. In this way, higher doses of the drug can be delivered to the cancerous areas and systemic toxicity can be reduced. Sometimes the drugs are heated to a specific temperature before they’re administered. This method is commonly used to treat ovarian cancer. Recently, another intraperitoneal method of delivery, where nanoparticles are used, has been gaining ground. This means that the drug is bound to nanoparticles. They’re used in a variety of intraperitoneal processes (ovarian cancer, mesothelioma and metastatic pancreatic cancer). Intraperitoneal nanoparticle chemotherapy is expensive and isn’t yet available in Latvia.

During intra-arterial chemotherapy drugs are delivered directly into an artery that feeds a tumour or larger metastases. This is usually done by invasive radiologists who contrast blood vessels beforehand and then evaluate which would be the most suitable to deliver the drug (vessels that decisively feed the tumour). Intra-arterial chemotherapy can be performed either as a single dose via a catheter or, once a special pump has been placed subcutaneously, via a catheter that is directly connected to the artery so the drugs can be delivered over a longer period of time. Throughout the world this method is used to treat kidney metastases (when the tumour is located in the colon), parts of the head and neck, in some cases of sarcoma, melanoma and stomach cancer and other tumours. In this way, it’s possible to deliver a larger concentration of a drug directly to the tumour, while reducing the amount of systemic toxicity in the body. Although this method initially seemed promising, significantly reducing the size of a tumour or its metastases, its positive effect on survival rates is still up for discussion.

Drugs can also be delivered intravesically or directly into the bladder. A catheter is placed in the bladder, the drug is administered and the catheter is closed. In cases like these, the patient is also asked to change positions so the drug can spread evenly throughout the bladder. After a period of time, the catheter is removed. Bladder surface tumours can be treated in this way with the BCG vaccine as well as other chemotherapy drugs.

During intrapleural chemotherapy drugs are administered to the pleural cavity – the space between the surface of the lungs and the lining of the lungs.  Typically, this method is used to treat pleural metastases and metastatic pleural effusions (cancerous fluid that accumulates in the pleural cavity), as well as pleural mesothelioma. First, a chest tube is inserted in the pleural space, then the accumulated fluid (which often makes breathing difficult, because pressure is placed on the lung) is drained and later chemotherapy drugs are introduced. In the majority of cases, this procedure is used to reduce terrible symptoms (shortness of breath), but it can also delay the accumulation of more fluid for a period of time. One drug, or a combination of drugs, including those used for targeted therapy, can be delivered intrapleurally.

In some cases, such as after a brain tumour has been surgically removed, chemotherapy implants can be placed in the space left behind, which are then gradually absorbed over the next 2-3 weeks. In this way, the drug is delivered directly to the area where the tumour was once located to destroy any remaining cells. Polymer implants can be administered not only in the tumour site, but also in the tumour itself (intratumorally). Studies have also been conducted in patients with deeply localized and inoperable tumours, such as pancreatic cancer. So far, this method isn’t available in Latvia.

Topical chemotherapy is the application of drugs directly to the skin as a cream. Such treatments are used for very superficial skin tumours, because the penetration of the drugs (penetration into the deeper tissues) is quite small. It’s mostly used on small superficial facial tumours. It’s also used on more widespread superficial facial tumours when, for whatever reason, other treatment methods aren’t available.

As you can see, there are numerous ways of administering chemotherapy. They can also be combined amongst themselves or with other treatment methods. Definitely ask your doctor about these possibilities and their positive results as well as their potential side effects.

Why does chemotherapy last so long?

Exactly how long your chemotherapy will last and whether it will be cyclical or continuous depends on the type of tumour, its progression and the planned treatment strategy (before surgery, after surgery, as the sole method or to treat metastases). The toxicity of the drug and the time needed to recover from its side effects is an important factor that is taken into account. The chemotherapy strategy is based on clinical trials and comparisons of different methods. Chemotherapy is typically prescribed in cycles, meaning that the body is given time to recuperate between doses of the drug. It’s possible that other drugs to combat the effects of chemotherapy may be prescribed during this time. The hope is that a specific number of cancer cells will be destroyed during each cycle and the tumour’s cell mass will have been reduced. How nice that would be if it were always true! Then you could continue the cycles until all of the cancer cells have been destroyed or until the body can no longer tolerate the side effects. However, things are quite different in real life. There will be patients whose tumours respond well to chemotherapy and the majority of their cancer cells will truly be destroyed, but there will also be patients whose prescribed therapy (according to guidelines and time-tested protocols) will be unsuccessful. The down time between chemotherapy treatments is necessary for the healthy cells to recuperate. Because tumour cells are genetically unstable, their regeneration takes longer than healthy cells. Chemotherapy can be administered as monotherapy (one drug) or as polytherapy (a combination of drugs). It can be delivered in one injection or as a long-term systemic infusion as an inpatient procedure (if the treatment is toxic or if the patient’s condition is grave), outpatient procedure (the therapy takes a couple of hours and the patient can go home afterward) or as a home treatment (topical creams, drugs taken orally). The specific treatment protocol determines how, how long, what type and how often chemotherapy is administered.  Chemotherapy can be prescribed once a week or once every two, three or even four weeks. Sometimes the drugs are administered for several consecutive days or with weekly intervals. This first treatment is considered to be the first cycle and future therapy will continue after 2, 3 or 4 weeks. This is also dictated by the protocols.

How long and how many cycles are planned is also dictated by the protocols, which are based on years of clinical experience and the results of clinical studies. Adjuvant or preventative chemotherapy usually lasts from 4 to 6 months. In some cases, it may take up to a year (testicular tumours and lymphoma). However, the duration of the treatment isn’t etched in stone and can change depending on the situation. In the case of metastatic tumours, if the tumour disappears completely, therapy is continued for another 1 or 2 times. If the tumour decreases in size during therapy, but doesn’t completely disappear, chemotherapy is continued until serious side effects occur. If the tumour continues to grow or if new metastases appear during treatment, then chemotherapy is put on hold. In such cases, a different drug is chosen or perhaps a different method. Similarly, if a severe side effect occurs that is a previously known reaction to the specific drug being used, the treatment protocol can be changed. This is why you’re supposed to have regular appointments with your doctor, so you can discuss any problems you might have during your therapy.

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