What can a Scalp Cooling Registry tell us about success rates?

Scalp cooling is the only clinically validated method of reducing chemotherapy-induced hair loss. Used in hospitals worldwide, scalp cooling helps many patients retain their hair during cancer treatment. The Scalp Cooling Registry analysed outcomes from 7,424 patients treated at 68 hospitals between 2006 and 2019. Published in 2024, its findings showed that 56% of patients did not require a head covering at their final chemotherapy session, with chemotherapy regimen identified as the most important determinant of scalp cooling efficacy.

For decades, chemotherapy-induced alopecia (CIA) has remained one of the most visible and distressing side effects of cancer treatment. Managing the psychological and emotional tolls of cancer is just as critical as managing the physical ones. Hair loss can severely impact a patient’s identity, privacy and confidence, making strategies for managing this side-effect crucial. The psychological impact caused by CIA can also extend to families, causing emotional distress for everyone including young children, who see evident physical changes to their loved one.

Scalp cooling has long been the only scientifically validated method of reducing chemotherapy hair loss. In the UK, the Paxman mechanised scalp cooling system is present in 99% of NHS and private hospitals. However, access to this treatment is still inconsistent across cancer centres in other parts of the world. 

The Scalp Cooling Registry provides large-scale evidence on the prevention of chemotherapy-induced alopecia.

Spanning 13 years, the registry documents the experiences of 7,424 patients who underwent mechanised scalp cooling across 68 hospitals. By examining patient outcomes across 24 different chemotherapy regimens, the study provides valuable insights into the factors that affect the efficacy of scalp cooling to mitigate chemotherapy-induced alopecia (CIA).

The results show a 56% success rate across the 7,424 patients, along with averages for specific chemotherapy regimens, indicating a higher success rate with taxanes.

The results also offer insights into whether gender, cancer type, lifestyle choices, chemotherapy naivety or other factors play a role in outcomes.

This Registry, the largest of its kind globally, serves as a crucial resource for clinicians delivering scalp cooling as a means of managing chemotherapy-induced hair loss. The efficacy of scalp cooling in delivering favourable results can no longer be denied.

The scalp cooling registry by Dr. Corina van den Hurk et al. represents the most comprehensive real-world investigation into scalp cooling – the largest to date. Rather than taking a strictly clinical perspective, it looked at patients being treated in hospitals. Conducted between 2006 and 2019 and published in The Oncologist in June 2024, the study collected data on patient demographics, chemotherapy protocols, hair characteristics and treatment experiences. It offers the largest-ever data set for scalp cooling research, underscoring its importance as a cornerstone of supportive cancer care.

Before taking a deep dive into the study and its results, it’s important for those unfamiliar with how scalp cooling works to appreciate the multiple mechanisms at play when chemotherapy patients put on the cold cap.  

Scalp cooling helps prevent CIA by lowering the temperature of the scalp and limiting the exposure of chemotherapy drugs. Despite its long-standing use, questions around mechanisms and efficacy remain among oncology professionals. However, through extensive research, it has been determined that a number of mechanisms of scalp cooling, when occurring in combination, render cooling of the scalp cytoprotective. [1] This contributes to reported clinical efficacy when used in conjunction with chemotherapy treatment for solid tumour cancers.  

Vasoconstriction 

Firstly, vasoconstriction in the scalp occurs as the cold cap reduces the temperature below the skin’s normal levels. The vasoconstriction results in a reduction of blood flow to between 20-40% of normal blood flow levels thereby reducing the extent of drug exposure to the hair follicles.  

Reduced Drug Uptake 

Secondly, active transport via membrane proteins, as well as passive diffusion, are the processes by which chemotherapy drugs (such as the anthracycline doxorubicin) enter the cell via the cell membrane. 

As demonstrated through biological studies using cell cultures, when the scalp is exposed to the colder temperatures of the cold cap, this results in reduced drug uptake across the plasma membrane of hair follicle cells. The cellular activity of the hair follicles is lower as is the kinetic energy and membrane fluidity. Low temperatures can cause structural changes to the plasma membrane, and this can dramatically reduce its permeability for chemotherapy drugs.  

Reduced Hair Follicle Cell Division 

Chemotherapy drugs are notorious for being unable to distinguish rapidly dividing healthy cells from the cancerous ones. This includes hair follicles, where during the active phase growth, the cells in the follicles, continually stimulated by growth factors, are in a highly proliferative state. As a consequence, these cells are more vulnerable to the cytotoxic effect of chemotherapy drugs. 

Scalp cooling reduces the metabolic activity of hair follicle cells, slowing down the cell division, rendering them less susceptible to chemotherapy drugs.  

Reduced Metabolic Activity 

Finally, the myriad of biological reactions that take place inside cells, such as metabolism, cell growth and cell death, is catalysed by enzymes – which are acutely temperature-dependent. A reduction in temperature may thus cause deceleration of cellular processes that can be involved in chemotherapy drug-mediated cytotoxicity. The deceleration of these processes could help attenuate toxicity and hair follicle damage. 

Along with these proven methods, the Registry addresses ongoing doubts around efficacy with robust data, affirming scalp cooling as an essential intervention for hair preservation.  

Key to the study’s success was its inclusivity, ensuring that a wider range of patients as possible, including both men and women, were assessed to build an even stronger case for scalp cooling. 

All patients eligible for scalp cooling during the study were invited to participate, regardless of whether they had received treatment for CIA before.  

The Registry’s depth is unprecedented and collected comprehensive data from both nurses and patients through questionnaires, covering a wide range of variables to thoroughly understand the determinants of scalp cooling success. 

The variables assessed included: 

• Demographics: Age, gender, cancer type, and treatment setting. 

• Chemotherapy Details: Regimens, doses, and infusion times. 

• Medical Background: Presence of liver metastases, previous chemotherapy, previous hair loss, or prior scalp cooling. 

• Hair Characteristics: Hair length, density, ethnic hair type, and any prior chemical manipulation. 

• Scalp Cooling Protocols: Pre- and post-infusion cooling times, hair dampening practices, and treatment tolerability. 

The Registry also collected additional information from 2013-2019, such as anthropometric characteristics (height and weight), lifestyle tendencies, pre-treatment greying, natural shedding patterns, hair colour, potential technical issues with the scalp cooling machine, and patient satisfaction with the scalp cooling process. 

The Scalp Cooling Registry was focused on efficacy, so what did the authors of the study use to determine if scalp cooling was effective?  

Hair loss and its extent can be a very subjective topic – what may seem like a failure to one patient is a huge success for another – the authors knew they would somehow need to quantify this into useful datasets.  

In addition to its primary objective, the published Registry results mean that expectations can now be better managed for patients, leading to more positive attitudes to treatment – more on this later.  

In order for the study to effectively and consistently evaluate the efficacy of scalp cooling, it used two primary criteria: firstly, patient-reported head covering usage during the final chemotherapy session and secondly, WHO alopecia scores.  

Head covering usage, whether a wig or scarf, is commonly used as an important outcome measure of efficacy, representing patient satisfaction with the treatment. Additionally, the WHO alopecia score, ranging from 0 (no alopecia) to 3 (total alopecia), was used to gauge the extent of hair retention. 

In some cases, despite a higher WHO alopecia score, the absence of a head covering indicated successful treatment, highlighting the subjective nature of patient satisfaction. 

The analysis of the 13-years’ worth of scalp cooling data yielded significant findings on the overall efficacy of scalp cooling that present significant and indisputable evidence on efficacy.  

• Overall Efficacy: 56% of patients did not require a head covering at the start of their final chemotherapy session, indicating satisfactory hair retention. 

• WHO Scores: 53% of patients reported minimal hair loss, with WHO scores of 0 or 1. 

• Chemotherapy Regimen: The study confirmed that the type of chemotherapy regimen was the only significant determinant of scalp cooling efficacy within its scope.

The study found that other factors, such as patient demographics, lifestyle habits (e.g., smoking and drinking), age, hair type, cancer type and gender, did not significantly influence scalp cooling outcomes. For instance, gender did not play a significant role in the success or tolerability of scalp cooling, nor in the likelihood of prematurely discontinuing the treatment. This finding supports the equal efficacy of scalp cooling for both male and female patients, underlining the importance of offering scalp cooling to all eligible patients.  

The studies confirmed that patients can anticipate a higher likelihood of hair retention when prescribed a taxane-based chemotherapy regimen. Overall, patients receiving taxanes had better results (78%) compared to patients receiving anthracyclines (40%) or a combination regimen involving anthracyclines (45%) as well as other more challenging regimens such as Irinotecan (36.5%).   

Whilst the data suggests more favourable results for taxanes, this data should be used to help clinicians set expectations for their patients, rather than dissuade them from accepting chemotherapy regimens that are less receptive to scalp cooling treatments. Even if retention may be challenging, patients should still be offered the opportunity to try scalp cooling.   

The study did not explore the well-researched principle of follicle protection that scalp cooling provides against high cumulative dosages of taxane drugs. [1] Alongside hair retention, evaluated in this particular study, follicle protection also encourages faster regrowth and helps to prevent persistent chemotherapy-induced alopecia, as evidenced through studies elsewhere in the world. 

It is worth noting that differences in the results seen in the three cohorts from the study could be attributed not only to chemotherapy regimen, but also to the size of the cohort and the increased awareness of scalp cooling protocols and usage.   

Dutch clinical staff from cohorts 2 and 3 may have already had years of experience with scalp cooling, leading to optimised cap fits and more accurate cooling times. In the 2024 manuscript by Brook et al., machine learning algorithms were used in the 3rd cohort study to identify extraneous variables which may have led to overfitting.    

Cohort 1 is 28% the size of cohort 2. Smaller cohorts can provide less information and context on efficacy. For example, patients receiving Vinorelbine (Vino) in cohort 1 displayed zero usage of a head covering whereas cohort 2, 22% of patients felt the need to cover their head. Whilst every patient is different, only 5 patients received Vino in the first study – a small sample size. In the second cohort, there were 34 patients studied that received the same drug. A larger n number gives a clearer picture of the efficacy of and patient experience with Vino, which is another reason why the Registry is so valuable to clinicians.  

The Registry findings have important implications for clinical practice, and affirmed that scalp cooling is effective for the majority of patients, with no immediate need for changes in current standard practices.  

Notably, the study highlights the gender equality in scalp cooling efficacy, demonstrating that both male and female patients benefit equally, having investigated non-gender specific cancers and analysing the data separately from those such as cancer of the prostate or breast. As a result, it is recommended that scalp cooling should be routinely offered to male patients as well if they are eligible, in addition to being as informed as female patients.  

The type of chemotherapy regimen remains the most critical determinant of scalp cooling success, with patients receiving taxanes seeing the best outcomes. However, the study also emphasises the need for further research into the unknown determinants that lead to varying outcomes among patients on the same chemotherapy regimen.  

Despite these uncertainties, the study encourages patients to continue scalp cooling, even if initial results are not satisfactory, particularly during anthracycline (AC) treatment. Whilst this study did not gather data on hair regrowth, it has been documented and exhibited in a number of other studies that scalp cooling can lead to quicker regrowth and even help to prevent persistent-chemotherapy induced alopecia – a lesser-known long-term side effect of certain regimens.  

The Registry also suggests that over time, increased knowledge and better application of scalp cooling protocols have led to better outcomes. Before the most recent cohort, average efficacy from the study was 50%. This increase to 56% in the latest publication emphasises that accurate deployment of the elements of the treatment such as cap fit, and pre- and post-infusion cooling times, are even more important in ensuring the best outcomes possible for patients.  

Whilst the paper itself offers an exhaustive analysis of specific chemotherapy drugs, the in-depth data allowed the researchers to train an algorithm to predict scalp cooling outcomes. It has also led to the creation of a scalp cooling outcomes calculator by the mechanised scalp cooling device manufacturer, Paxman.  

Here, patients themselves can access the calculator when researching scalp cooling. Selecting their chemotherapy drug and dosage allows them to gain an estimate on the likelihood of retaining half of their hair. This tool, grounded in the experiences of 7,424 patients, allows one to make a more informed decision around their choice to scalp cool and sets more realistic expectations.  

At the time of the 2024 publication, the team behind the Dutch Registry identified an international registry as a possible next step after collecting scalp cooling data from more than 7,000 patients in the Netherlands.

An international scalp cooling registry would help to more accurately determine discrepancies in scalp cooling between countries and how country-specific factors influence outcomes, such as: availability, accessibility and affordability. The current iteration of the Registry acknowledges that there is a lack of substantial data on variety of hair types and ethnic representation within the study, something which could be better tackled on an international stage. 
 
A registry of this scale would increase the diversity of the cohort, addressing disparities and enhancing our understanding of scalp cooling across different healthcare settings. Different countries have slightly different approaches to drugs, depending on regulatory approvals, cost, physician preferences etc. An international registry will allow the team to collect more data, particularly for regimens that are not used within the Netherlands.  

It would also aim to help increase scalp cooling efficacy, improve clinical reviews, educate providers and further the understanding and recognition of the impact of hair loss for the patient. 

The Scalp Cooling Registry solidifies scalp cooling as the gold standard for preventing chemotherapy-induced hair loss. Its comprehensive dataset and robust analysis provide clinicians and patients with the strongest evidence yet of its efficacy.

For patients and clinicians alike, it presents a number of crucial recommendations.

Universal access: Scalp cooling should be routinely offered to all eligible patients, regardless of gender or expected efficacy.

Setting realistic expectations: Tools like the Outcomes Calculator help guide patient decisions and ensure satisfaction.

Standardised protocols: Consistent application of best practices, such as proper cap fit and cooling times, is critical.

Speaking about the significance of the registry data, Nik Georgopoulos PhD, BSc, FHEA, co-author and associate professor at Sheffield Hallam University, said, “The publication of the Registry data represents a milestone in clinical scalp cooling research. By analysing the findings from such a large patient cohort, the great statistical power of the study provides the strongest ever evidence for the efficacy of scalp cooling in protecting cancer patients from chemotherapy-induced hair loss”.

As the field of oncology continues to advance, the Registry serves as a reminder that patient-centred care goes beyond survival. By preserving hair and therefore privacy, identity and wellbeing, scalp cooling enhances the quality of life for thousands of patients worldwide.

Further reading

Results of the Dutch scalp cooling registry in 7424 patients: analysis of determinants for scalp cooling efficacy. Toni S Brook, Tanja Seetsen, Marcus W Dercksen, Annemarie van Riel, Veerle A Derleyn, Johan van den Bosch, Johannes W R Nortier, Andrew Collett, Nikolas T Georgopoulos, Jarek Bryk, Wim P M Breed, Corina J G Van Den Hurk. The Oncologist. 2024;, oyae116, https://doi.org/10.1093/oncolo/oyae116

Scalp cooling for hair preservation and associated characteristics in 1411 chemotherapy patients – Results of the Dutch Scalp Cooling Registry. Corina.J. van den Hurk, Mijke Peerbooms, Lonneke V. van de Poll-Franse, Johan W. Nortier, Jan Willem W. Coebergh & Wim P. Breed. The Oncologist, 2012; 00: 1–8