The truth or dares in oncology

Prof Carol-Ann Benn uncovers the truth or dares in the field of oncology.

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Family holidays usually involve cards, games, and a fair amount of playful arguments. One game that often comes to mind is Truth or Dare. The premise is simple: if you can’t answer a question truthfully, you must accept a dare. This game is now available online, much like how we seek out information. 

If you don’t play games, maybe you watched that series MythBusters. Consider this my version of myth busting or truth or dare in the field of oncology. 

The difference between a truth and a dare is that a truth can be verified by showing data. A dare, on the other hand, is often based on some facts, but due to a lack of significant in-depth studies, potential harm can befall those who take the dare. 

Half-truths that became dares

A good example of this occurred in the 1950s when drugs were marketed without detailed studies, resulting in unintentional harm. Two drugs from this era come to mind: thalidomide and tamoxifen. 

Thalidomide was initially introduced as a medicine to help pregnant women suffering from nausea. However, without thorough studies, it led to women giving birth to children with severe limb developmental issues. As a result, the drug was banned. Despite this, scientific oncology researchers continued to study thalidomide, and many years later, it resurfaced as an extremely effective treatment for multiple myeloma.

In a less dramatic story, tamoxifen was introduced in the 1960s as a morning-after contraceptive pill. However, it was not an anti-oestrogen. Instead, in young women, it caused ovarian oestrogen stimulation, leading to increased egg production (acting more like a fertility drug) and resulting in many pregnancies. After an additional 10 years of research, it was discovered that the drug could switch off cells in the breast and be used to treat breast cancer.

Truth vs dares

1. Radiation exposure during mammograms

Studies indicate that the radiation exposure from a typical mammogram is relatively low, with an average effective dose of approximately 0.4 to 0.5 mSv. While there is a theoretical risk of radiation-induced breast cancer, the benefits of early breast cancer detection through mammography significantly outweigh this risk, particularly for women aged 40 to 50. Modern digital mammography has further reduced radiation exposure compared to older screen-film methods.

Research shows that there are approximately 125 cases of breast cancer attributed to radiation exposure (from a long time ago), resulting in an additional 16 cancer-related deaths. In contrast, screening has been shown to prevent around 968 breast cancer deaths due to early detection, giving a benefit-to-radiation risk ratio of about 60 to 1.

On average, the radiation exposure during a mammographic exam is about 0.5 mSv. To put this into perspective, this amount of radiation is like what a person would receive during a flight from New York to Athens, Greece. In summary, yes, there is some exposure to radiation during a mammogram, but it’s at a very low dose.

2. A needle biopsy causes cancer to spread 

The data indicates that the safest method for diagnosing breast cancer is through a core needle biopsy. While studies suggest that needle biopsies are generally safe, they do carry a slight risk of displacing cancer cells (seeding), which could potentially lead to local recurrence or distant metastasis. 

When this does happen, it’s referred to as tumour seeding. This process occurs when the needle inserted into a tumour during the biopsy dislodges and spreads cancer cells. Tumour seeding may also be called needle tract seeding because the cancer cells can grow along the path created by the needle.

However, the advantages of biopsies for diagnosis and treatment planning generally outweigh these risks, and there is no conclusive evidence that biopsies significantly increase overall survival risks. 

Although needle tract seeding was reported in 22% of patients, analyses have shown no increased risk of local recurrence or death following a needle biopsy. Most of the evidence indicates no significant association between needle biopsy and the risk of local recurrence or death. This information is based on a Cochrane review of the literature.

The rarity of tumour seeding

While cancer spread after a biopsy can theoretically occur, it’s extremely rare. Several studies have confirmed how rare tumour seeding is. 

• A 2008 review found that needle tract seeding occurred in 2.7% of liver cancer biopsies.
• A 2015 study reviewed previous research and discovered the incidence of needle tract seeding was less than 1%.
• A 2019 study followed 42 patients with bladder cancer who underwent a core needle biopsy. After monitoring them for 28 months, no instances of tumour seeding were reported.
• A 2024 review article analysed previous studies on tumour seeding from breast needle biopsies and concluded that undergoing a needle biopsy doesn’t significantly affect the likelihood of breast cancer recurrence, its spread to other parts of the body, or overall survival.

If you have concerns about a biopsy, it’s advisable to ask your doctor why they recommend it and to discuss the risks associated with both having and not having the procedure.

3. A mastectomy or bilateral mastectomy is best for young women 

A mastectomy, or bilateral mastectomy, may be considered a suitable option for younger women, those at genetic risk for breast cancer, or individuals who wish to avoid chemotherapy or radiation. This is a bit of a dare. If you have a mastectomy to avoid radiation but there is cancer in the glands (found on pathology even though not evident on your radiology) you then need radiation anyway. Also, you can’t avoid chemotherapy or other oncology treatment as this is based on the behaviour of your cancer and not on what surgery you do.

Studies indicate that bilateral mastectomy is a viable choice, particularly for young women and those with a genetic predisposition to breast cancer, such as those with BRCA1 or BRCA2 gene mutations. This preventive surgery, note preventative by removing both breasts, can significantly reduce the risk of developing breast cancer by 90 – 95% in women with these mutations. 

However, this approach is not a perfect solution and comes with potential drawbacks. 

Once you have cancer, it’s more important to treat the cancer based on how it behaves and consider if you want your bilateral mastectomy later.

Negative aspects of mastectomy

• Surgical risks (bleeding, infection, and pain).
• Body image and psychological effects from changes in body image and self-esteem, potentially resulting in anxiety and distress.
• Some women may also experience alterations in sexual function due to loss of nipple sensation and changes in breast sensitivity.
• Most important of all is the irreversible nature.   

Mastectomy is a permanent procedure. While it significantly reduces risk, it does not guarantee that breast cancer will never develop, as some breast cells may remain. 

To quote from the recent 19^th St. Gallen Breast Cancer Conference: a mastectomy is just a large breast-saving operation as you can’t take out all the breast tissue anyway.

Mastectomies vs. breast-conserving surgery 

In cases of early-stage breast cancer, research indicates that both breast-conserving therapy (BCT) and mastectomy provide similar survival rates and breast cancer-specific survival rates. While some studies suggest that BCT may result in slightly better survival outcomes, particularly for certain subtypes like luminal A breast cancer, the overall trends across all breast cancer types reveal important insights.

At the five-year mark, the overall survival rate for the BCT group was 96.49% while for the mastectomy group, it was 88.64%. At ten years, these rates decreased to 88.69% for BCT and 74.09% for mastectomy.

4. Chemotherapy kills normal cells 

Chemotherapy affects both cancer cells and normal cells, leading to various side effects. However, normal cells typically have a greater capacity to repair and recover from the damage caused by chemotherapy. 

In contrast, cancer cells are more likely to be permanently harmed or destroyed. Chemotherapy drugs primarily target fast-growing cells. This includes not only cancer cells but also some normal cells, such as those in the bone marrow, hair follicles, and the lining of the digestive system.

In summary, while chemotherapy impacts both normal and cancer cells, normal cells can often recover and resume their regular functions, whereas cancer cells are more prone to enduring damage or destruction.

5. Can you dare not to take your endocrine treatment?

Yes, endocrine treatment is considered essential for hormone receptor-positive breast cancer. It’s a crucial part of the treatment plan for these types of breast cancer, often used alongside other treatments like surgery, radiation, or chemotherapy. 

Endocrine therapy is a vital part of the treatment plan for hormone receptor-positive breast cancer, helping to prevent recurrence, improve survival, and slow or stop the growth of cancer cells. 

A five-year duration of endocrine therapy can reduce recurrence by 50% and mortality by one-third. Extended therapy beyond five years offers further protection but also increases the risk of side effects. For example, 10 years of endocrine therapy has been associated with the greatest reduction in contralateral breast cancer (new primary cancer in the opposite breast of a patient who has already had breast cancer).

After a median follow-up of 30.6 months, a 32% risk reduction was found, corresponding to an absolute benefit in terms of disease-free survival of 4.7% at three years after randomisation.