What Is Prophylactic Cranial Irradiation?

Prophylactic cranial irradiation (PCI) is a type of radiation therapy used to prevent the spread (metastasis) of lung cancer from the lungs to the brain. The brain is among the most common site of metastases in people with advanced lung cancer, along with the liver, bones, adrenal glands, and other parts of the lung.

Since 2007, PCI had been widely accepted as the standard of care for people with small cell lung cancer (SCLC), an uncommon and aggressive form of lung cancer. In 2017, doubt was cast about the value of the procedure when studies published in Lancet Oncology concluded that PCI did nothing to improve survival times in people with extensive-stage SCLC, an advanced form of SCLC.

Although prophylactic cranial irradiation is still used successfully in people with limited-stage SCLC, its use has dropped off significantly in recent years.

Purpose of the Procedure

Small cell lung cancer has a strong tendency to spread to the brain. Although chemotherapy is usually good at controlling the disease (at least for a while), the drugs have difficulty penetrating the blood-brain barrier that surrounds and protects the brain. Because of this, cancer cells that enter the brain have an opportunity to proliferate.

Roughly 10% of people with SCLC have brain metastases at the time of diagnosis, while 50% will develop brain metastases during the course of their disease, according to a 2017 review in Current Oncology.

Prophylactic cranial irradiation ("prophylactic" meaning preventive) is meant to reduce the odds of brain metastasis proliferation by preventing the growth of cancer cells before there are any signs or indications of metastasis.

Evidence and Controversy

In a 2007 study, Dutch researcher Ben Slotman and colleagues reported that PCI increased one-year survival rates in people with limited-stage SCLC from 13.3% to 27.1%—a nearly two-fold increase—while reducing the risk of brain metastases by nearly threefold.

Even so, the median survival time increased from 5.4 months to only 6.4 months, a significant improvement but one that is tempered by the severity of side effects experienced by many people.

In recent years, some researchers have questioned whether the widespread use of PCI, particularly in people with extensive-stage disease, is even appropriate.

In 2017, Japanese scientist Toshiashi Takahashi and colleagues demonstrated that people with extensive-stage SCLC actually have lower survival times when treated with PCI compared to those who are left untreated. The investigators concluded that PCI is "not essential" for people with extensive-stage SCLC and that routine monitoring of brain metastases with magnetic resonance imaging (MRI) is more appropriate.

In the aftermath of the findings, the use of PCI has dropped significantly, according to a 2019 study from the University of Texas MD Anderson Cancer Center in Houston. According to the investigators, 78% of oncologists offered PCI to patients with extensive-stage SCLC prior to the Takahashi study, and that number dropped to 38% after publication of the research.

Risks and Contraindications

Prophylactic cranial irradiation can play an important role in the prevention of brain metastases by killing metastatic cancer cells in the brain.

The radiation dose is far lower than that used to cure solid tumors but significantly higher than that used for imaging tests like computed tomography (CT) scans. The repeated exposure to radiation of this level can lead to neurotoxicity in which brain cells are either disrupted or permanently destroyed.

PCI not only causes short-term side effects but can lead to long-term harm, some of which may not be apparent until months or years after treatment.

The most common short-term side effects include:

• Headache
• Fatigue
• Hair loss (often permanent and complete)
• Nausea and vomiting
• Skin redness, peeling, or blistering
• Loss of appetite
• Weight loss
• Difficulty swallowing

The long-term effects can be more profound.

The risk tends to be greatest in seniors, people who take anti-epilepsy medications, and those with diabetes or a history of stroke.

In some people, PCI can disrupt blood vessels in the brain, causing "micro-bleeds" and increasing the risk of an ischemic stroke.

Contraindications

Despite this, PCI has relatively few contraindications. Because PCI can weaken blood vessels in the brain, it is never used in people with cerebrovascular conditions such as stroke, aneurysms, and vascular malformations. It is not used on people with epilepsy either, as it can increase the frequency and severity of seizures.

PCI should also be avoided in people with poor performance status, meaning those who are unable to take care of themselves. People who have a short life expectancy should also avoid PCI as it is likely to cause more harm than good.

PCI is not used in people with non-small cell lung cancer (NSCLC), the more common form of the disease, and it is increasingly avoided in people with extensive-stage SCLC.

Before the Procedure

The decision to use prophylactic cranial irradiation is a very personal one. Due to the increased risk of neurotoxicity and neurocognitive impairment, the benefits and risks need to be carefully weighed in tandem with your long-term prognosis.

In addition, your healthcare provider will need to assess your performance status—usually rated on a scale of 0 (completely active) to 4 (completely disabled)—to determine if you can tolerate treatment.

If you are a candidate for PCI, you will be scheduled to meet with a specialist known as a radiation oncologist who will begin early preparations and walk you through the procedure.

Timing

PCI is delivered in a series of treatments, given once or twice daily for five days a week for up to three weeks. Each radiation treatment only lasts a few minutes, but factoring in preparation and waiting time, you should expect to be there for 45 minutes to an hour.

If more than one radiation dose is required, you will need to wait four hours between doses. As inconvenient as this may seem, there is evidence that the approach is more effective.

Location

Prophylactic cranial irradiation is most often performed in the radiology unit of a hospital, although there are specialized radiology units in certain cancer treatment centers.

PCI is performed with a machine called a CT simulator, which looks like a normal CT scanner but delivers a higher dose of focused radiation. The machine is composed of a flatbed that slides in and out of a donut-shaped gantry that delivers the radiation dose.

What to Wear

As you may change into a hospital gown, you should wear comfortable clothes that you can easily remove and put back on. Leave jewelry and other valuables at home. Eyeglasses and hairpieces will also need to be removed.

Food and Drink

There are no food or drink restrictions associated with PCI.

Cost and Health Insurance

The cost of PCI can vary by location and facility but can easily run into the tens of thousands of dollars. Today, health insurance companies are less likely to approve PCI for people with extensive-stage SCLC and will almost invariably reject requests for use in people with NSCLC.

To calculate your out-of-pocket expenses, ask for a cost estimate from the radiology unit and check what portion you are responsible for based on the copay/coinsurance schedule in your insurance plan (both before and after the deductible). You should also check what your out-of-pocket maximum is; this is the maximum amount you have to pay out of pocket for the policy year.

If the out-of-pocket costs are exorbitant, ask the radiology unit if they offer a no-interest installment plan or financial assistance programs. Larger hospitals are more likely to do so.

What to Bring

Be sure to bring your driver's license or government ID, your health insurance card, and an approved form of payment if copay or coinsurance costs are required upfront.

Simulation

Before your first treatment is scheduled, you will need to attend a planning session called a simulation. This is used to calculate the correct radiation dose and map the treatment area with both the radiation oncologist and radiation therapist.

To ensure your head is in the correct position for each and every treatment, a mold of your face will be created using a grid-like thermoplastic material that quickly hardens when heated. Once your head is correctly positioned on the flatbed, the radiation therapist will smooth the material along the lines of your face and wait for it to harden. The entire process takes around 30 minutes.

Unlike other forms of head and neck radiation, which direct a focused beam of radiation at the exact location of a tumor, PCI delivers a more generalized array of radiation. Even so, the radiation team will take precise measurements, making marks on the face mask to ensure that other tissues remain untouched.

As part of the simulation, the radiation team may perform a CT scan to confirm what's referred to as the informed field of treatment. Low-dose X-ray beams (beam films) can help record your head position once it is correctly placed.

During the Procedure

On the day of the procedure, arrive at least 15 minutes beforehand to register and settle in. PCI is typically overseen by the radiation therapist with the aid of a radiology nurse.

Preparation

Once registered, you will be taken to the back and you may be asked to undress from the waist up. A hospital gown will be provided for you to change into. You will likely be able to leave on your pants and socks, but you may need to take off your shoes.

The nurse will then take your weight and vital signs, which will be monitored for the duration of PCI therapy. After your first session, the nurse will also check if you are experiencing any side effects from the previous session.

Throughout the Procedure

Prophylactic cranial irradiation is relatively straightforward. Once you are laid in a supine (face-up) position on the flatbed, the radiation therapist will correctly position your head and cover it with the pre-molded face mask.

With the preset coordinates and radiation dose, the radiation therapist can conduct the entire procedure from behind a protective screen. A two-way intercom allows you to communicate back and forth.

The flatbed is then moved remotely into the CT gantry, where radiation doses of between 12 and 18 gray units (Gy) are used. (By way of comparison, solid tumor cancers are treated with 60 to 80 Gy, while lymphomas are treated with 20 to 40 Gy.)

You will hear whirring sounds during the procedure but otherwise feel nothing.

Post-Treatment

Once the procedure is complete, the face mask is removed and you can put your clothes back on. If you are experiencing side effects of any sort, let the nurse or radiation therapist know.

Most people can drive themselves home after undergoing PCI.

After the Procedure

It is not uncommon to experience side effects with PCI therapy, some of which can get worse as the treatment progresses. There are certain things you can do to manage them.

• Headache: Tylenol (acetaminophen) is usually the best option for treating headaches. Aspirin and other nonsteroidal anti-inflammatory drugs, on the other hand, may cause bleeding and promote microbleeds. Because brain irradiation induces encephalitis (brain inflammation), the steroid drug dexamethasone may be prescribed to relieve inflammation.
• Fatigue: Radiation-induced fatigue is best treated by getting plenty of rest. A little exercise or a walk around the block can also help both physically and mentally.
• Skin irritation: Radiation-induced erythema (skin redness) can be aggravating and lead to peeling and blistering, particularly in people with fair skin. You can better manage this by taking cool showers, avoiding harsh soaps and fragrances, moisturizing regularly, and dusting the affecting skin with cornstarch (not talc) to keep the skin dry.
• Eating problems: PCI can sometimes cause dysphagia (difficulty swallowing), as well as heartburn and nausea. To help overcome this, eat softer food or soups. You can also meet with a dietitian to discuss dietary strategies during and after PCI therapy. To reduce nausea, your healthcare provider may prescribe an antinausea drug like Zofran (ondansetron), or trying sipping ginger tea or ginger ale.
• Hair loss: Treatment-induced alopecia (hair loss) can be very distressing. There is little you can do if this occurs as a result of PCI, but it's important to remember that not everyone experiences hair loss. If it occurs, there are companies you can contact that make wigs especially for people with cancer and other ways you can cope both physically and emotionally.

Follow-Up

Because prophylactic cranial radiation is preventive, the only measure of success is the absence of brain metastases on imaging studies. Your oncologist will schedule routine CT, MRI, or positron emission tomography (PET) scans to monitor for any signs of metastasis, not only in the brain but also in other organs and your bones.

Your healthcare provider will also monitor for any neurocognitive problems that may arise.

A Word From Verywell

Prophylactic cranial irradiation can help extend life and prevent disease progression in people with certain types of small cell lung cancer, but it comes with risks. If your healthcare provider recommends PCI, you can discuss the benefits of treatment and the potential risks to make the choice that's best for you as an individual.

Speak with members of your support network, including healthcare providers, counselors, friends, and family. Join an online or in-person support group to meet others who have undergone PCI themselves.

There is neither a "right" nor "wrong" choice. There is only informed choice, and that begins and ends with you.