treatment

Cancer treatment

Key points:

  • Cancer treatments involve either killing cancer cells or at least stopping them from growing and spreading.
  • Treatment options have increased dramatically in recent years.
  • Treatment effectiveness varies between cancer types – there are highly effective treatments in some areas (e.g. breast and prostate), but less effective treatments in others (e.g. pancreatic, brain).
  • Over 50% of cancer patients treated today will survive at least 10 years.  Survival rates for breast and prostate cancer are much higher.
  • Traditionally, surgery, chemotherapy, hormone therapy and radiotherapy have been the mainstays of cancer treatment, but now there are several new classes of drugs that target specific cancer pathways. These are called targeted treatments.
  • In addition, new immunotherapies are showing promising results and hold great hope for effective future treatments.

What is cancer treatment?

This seems an obvious question, but some terminology is important. A cancer treatment is normally thought of as something that:

  • Kills cancer cells (either directly or indirectly);
  • Prevents or slows cancer cell growth; or
  • Helps to prevent cancer recurrence.

In other words, all treatments try to kill cancer cells or at least stop them from growing and spreading. Cancer treatments impact what doctors call “outcomes”, which are mostly measured in terms of extending life. Perhaps the most cited outcome measurement is the five or ten-year survival rate.

The good news is that the overall ten-year survival rate for cancer is now above 50%.[1] This is largely due to better treatments and earlier detection (broadly speaking, cancer is much easier to treat when caught early and confined to one location).   These topline figures, however, represent a blending of all cancer types, and while great strides have been made in some areas (testicular, prostate, breast), the progress in other areas (e.g. brain, pancreatic) has been much slower.

How to think about treatment

At Curve, we encourage patients to take an active approach to their treatment and recovery. This is for the simple reason that in our collective experience of treating thousands of patients over decades it is the patients who take an active interest in their health who tend to do better.

Being active means not only understanding what treatments you are having and how they work, but also looking for other things that can be added to help. These are things (such as diet, exercise and stress management) that are not normally recommended as frontline treatments because they have not all been proven in medical trials to the high standards required by doctors but nonetheless have a reasonable scientific basis (particularly in certain types like breast, prostate, bowel). Also, importantly, they tend to have little to no downside, only upside. In risk management terms, these things have asymmetric risk-reward profiles. Common and medical sense tells us they are worth the time and effort.

It is important to note, however, that is not any old intervention that falls into this “common sense” category – there must be a reasonable scientific basis indicating potential upside, and few if any (or, even better, only positive) side effects.   If patients don’t insist on a reasonable scientific basis before acting they put themselves at the mercy of the many charlatans peddling dubious or fake treatments.   These are things for which there is no reasonable scientific basis or in some cases evidence of harm, including financial harm or toxicity as many are very expensive.

These fake treatments are particularly dangerous if they are suggested as alternative remedies. “Alternative” in this context means that they are suggested as substitutes for doctor led treatments like chemotherapy, radiotherapy, surgery, and so on. These are not to be confused with “complementary” therapies, which are done in addition to doctor led therapies.   In short, alternative therapies are to be avoided whereas (some) complementary therapies are to be embraced.

In deciding how to respond to cancer, it is ultimately about finding a balance – patients need to avoid things for which there is no reasonable scientific basis, but keep an open mind and not be so strict that they miss things that might really help. Graphically it looks like this:

 

Curve is all about helping patients get the balance right – it’s about taking the best of the green zone (which your doctors will advise on) but adding to it from the yellow zone, while avoiding the red zone. Put another way, Curve helps patients sort the yellow and red zones by steering them towards things that have a reasonable scientific basis (the yellow zone) and away from things that are not supported (the red zone). Currently patients are left to their own devices to sort the yellow from the red, and normally try to do this online, but that is difficult and overwhelming. We explain this and other important topics in more detail in our video series.

Types of Treatment

Until relatively recently, most patients received one or a combination of surgery, radiotherapy, chemotherapy, or, in the case of hormone driven cancers like breast and prostate, hormone therapy.   In recent years, however, the treatment options have increased significantly as new drugs have been developed. These fall in to two main categories – targeted therapies and immunotherapies.

We will now discuss each main treatment category in turn.

Surgery

Surgery has traditionally been and remains the most effective treatment. When cancer is contained in a limited area, often it can be surgically removed, resulting in full cure. Surgery has been used as a response to cancer since the late nineteenth century when it was realized that tumors could be cut out.

Surgery has come a long way. Advancements in technology and knowledge mean it can be far less invasive. For example, 35 years ago radical mastectomy was still used for breast cancer, deforming the chest wall. Now, in many cases, breast surgery is minimally invasive leaving the breast largely in tact.

Ultimately, surgery will largely disappear as a cancer treatment, replaced by drugs that will overtake it in effectiveness.

Radiotherapy

Treatment with radiation was first used in cancer over a century ago. Initially, crude radium, which had been discovered in 1898 by Marie and Pierre Curie, was used as the source of radiation, but we now have highly sophisticated accelerators that delivery very precise doses of radiation to kill cancer cells, resulting in effective treatment.

Radiation works as a treatment by damaging cell DNA and thereby causing a cell either to stop dividing or to commit cell suicide, which is called apoptosis.   Radiation is therefore more effective at killing rapidly dividing cells like cancer cells. The key to effective treatment is killing cancer cells while leaving normal cells alone. This in turn requires delivering the right amount of radiation to tumors only, so that adjacent tissues are left untouched.

Radiation treatment is typically done over many weeks as it takes time for the cells to be damaged and then die. The total dose of radiation is broken into parts (called fractions) and delivered on a specific timetable. For example, a typical radiation course for many breast cancer patients is three to five weekly sessions after surgery and / or chemotherapy. For breast patients, radiotherapy is typically used after breast-conserving surgery (as opposed to mastectomy, where the breast is removed).

Radiation treatment is normally administered via a machine called a linear accelerator; though in some cases radioactive beads are surgically implanted in the relevant area (e.g. breast, prostate or skin). This is called brachytherapy and is an effective treatment.

Chemotherapy

Treatment by chemotherapy is the use of specific chemical compounds (drugs) to kill cells in the body. The difficulty with chemotherapy is that it is a systemic treatment and so impacts many normal cells. The aim therefore is develop treatment compounds that target cancer cells only while leaving healthy cells untouched.   A treatment’s effectiveness is therefore measured by the extent to which it achieves this aim.

Until relatively recently most drugs tried to achieve this by targeting cells that divide rapidly, as cancer cells do. The drawback of this approach is that the body also contains some healthy cells that divide quickly, such as those that line the gut and mouth, as well as those that make hair grow. In recent years, drugs have become more sophisticated, targeting specific cancer pathways. These are called targeted therapies / treatments and are discussed separately below.

The effectiveness of chemotherapy varies massively. In a few limited cases it can be curative for advanced disease (e.g. Hodgkin’s disease, childhood leukemia and testicular cancer). At the other end of the spectrum are cancers where it normally has a low response rate (e.g. lung and stomach cancer). In the middle are other types where it is effective in slowing cancer’s advance but where cure is unlikely (e.g. breast and prostate cancer). Chemotherapy can also be given after surgery as so-called ‘adjuvant chemotherapy’. This is commonly used for breast or bowel cancers. Chemotherapy is given after the operation to ‘mop up’ any cancer cells that have escaped from the primary cancer that has been removed.

Chemotherapy treatment often involves multiple drugs[2] being prescribed at once as cancer cells tend to adjust more slowly to multiple drug regimes.[3] Common chemotherapy drugs include epirubicin in breast and docetaxel, used in multiple types (including breast and prostate).

Hormone treatment

These treatments are used in cancers that rely on hormones to grow (e.g. prostate, and some breast and cervical cancers). These treatments generally reduce levels of circulating hormones or block the interaction of the hormone with its receptor and thereby stifle cancer growth and / or reduce the chances of recurrence.

Drugs like tamoxifen block the interaction of estrogen with the estrogen receptor in breast cancer patients who have estrogen receptor (ER) positive cancers.

Immunotherapies

One of the reasons that cancer cells are able to survive and spread in the body in cancer patients is that the body’s immune system can be tricked so that it doesn’t recognize and eliminate the cancer cells. They are after all a mutated form of our own cells and so the immune system has a hard time recognizing them. It is also thought that some cancer cells give off signals that tell the immune system that they should be spared execution.

In broad terms, immunotherapies treat cancer by helping the immune system to better recognize cancer cells. For example, checkpoint inhibitors help a certain type of immune cell (a type of white blood cell called a T Cell) identify and kill cancer cells.

Another group of treatments that use the immune system are called monoclonal antibodies. These are produced in a lab and designed to attach to specific targets found on the outside of cancer cells. Once attached the immune system is able to identify those cells as cancerous and attack them.

Treatments that help the immune system to better attack cancer cells are amongst those giving the greatest hope of developing breakthrough treatments in the near term. For example, a new treatment in this category, called adoptive cell transfer, involves removing T Cells from the body and either identifying and then growing the most effective ones or genetically engineering them to kill cancer cells.[4]

Targeted Treatments

Targeted treatments are newer drugs that seek to interfere with a specific cancer pathway. Pathways are the routes through which cancer act to grow and spread. Although cancer is the umbrella term for a collection of 200 different diseases, there are common pathways in most cancers. These are also referred to as the hallmarks of cancer. For example, all cancer involves uncontrolled cell growth. Another pathway is called angiogenesis.[5] Inflammation is a further pathway– cancer thrives in an inflammatory environment. We discuss these and other pathways in our video series, providing a helpful model for understanding how cancer can be targeted, not just by drugs but by other interventions too like diet and exercise.

Targeted treatments work by interfering with these pathways. For example, a relatively new group of drugs called kinase inhibitors treat cancer by interfering with a cell’s ability to divide. Kinases perform signalling functions in cells, telling them to do certain things including dividing. By interfering with this process, cells can be prevented from dividing.

Another new group of drugs treat cancer by interfering with the body’s ability to create new blood vessels. These are called angiogenesis inhibitors. These are used in multiple cancer types.[6]

Yet another class of targeted treatments is PARP inhibitors, which interfere with the ability of cancer cells to repair their DNA. These are used in multiple cancer types, including ovarian and some breast cancers.

Monoclonal antibodies are also used as a targeted treatment. In this context they are used to deliver toxic substances directly into cancer cells.

Stem Cell Transplants in Cancer Treatment

Finally, some cancers (e.g. leukemia, myeloma) can be treated with stem cell treatments, also known as bone marrow transplants. This treatment is used to replace the body’s immune system after high-dose chemotherapy and sometimes radiotherapy.

The Future of Cancer Treatment

Within two decades most cancers that we have not been able to cure will be controllable, by which we mean there will be enough treatments available to keep the cancer in check, to stop it spreading. Most patients in this position will lead long and normal lives, much like patients with other chronic diseases do (e.g. diabetes, HIV).

Cure will still be sought but it will not be the only satisfactory outcome, and the fear that cancer will lead to death will be replaced by an acceptance that treatments can manage the disease over long periods of time. The role of diet and exercise will be increasingly important to potentially augment the efficacy of these treatments and lessen their side effects.

https://www.cancerresearchuk.org/health-professional/cancer-statistics/survival
For example, the TAC breast cancer regime involves three drugs given to breast patients (Docetaxel, Doxorubicin (also called Adriamycin), Cyclophosphamide)
Chemotherapy effectiveness typically reduces over time as cancer cells mutate and learn to sidestep the drugs
See, e.g., https://www.malaghan.org.nz/what-we-do/cancer
Angiogenesis is the process by which the body creates new blood vessels. This occurs when the body is growing or healing. Cancer requisitions this process – it tells the body to create new blood vessels so that tumors can keep growing (they need nutrients to survive, which are carried by the blood)
In breast cancer, angiogenesis inhibitors are rarely used as the data supporting their effectiveness is limited. In is unclear why some breast cancers don’t respond well to this class of drugs

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