Clinical trials for breast cancer treatments

Access innovative therapies that may be compatible with your diagnosis

Today there are 174 clinical trials for breast cancer in Spain:

Selecting participants
Participation covered
Upcoming selection

Find out which sites you can participate in with our clinical trial finder.


What is the treatment for breast cancer?

Breast cancer is the most studied tumor in the world, thus there are currently several treatment options commonly used in clinical practice. It is important to remember that breast cancer can affect both women and men (about 1% – 2% of breast cancer diagnoses are men).  


The type of treatment administered will depend on the patient’s health condition, the tumour’s characteristics and the type of breast cancer present, such as HER2 positive or triple negative. Another critical factor in determining the most appropriate therapy is the tumor stage: whether it is localized or has spread and metastasized


The intent of the treatment plan can be adjuvant or neoadjuvant. The difference between adjuvant and neoadjuvant lies in the time at which it is administered: 


  • Adjuvant is the treatment given after surgery

  • Neoadjuvant is the treatment given before surgery

Therapies for carcinoma in situ (stage 0)

The disease is at an early stage, so it is highly treatable. Both lobular carcinoma in situ and ductal carcinoma in situ, at this stage, have malignant cells located in the lining of a breast duct, i.e. they have not migrated into adjacent breast tissue. Conventional treatments for these cases are: 


  • Breast-conserving surgery (lumpectomy): the tumor and some of the surrounding healthy tissue are removed, avoiding removal of the entire breast. The medical team may also consider removing lymph nodes for study to rule out the possibility that the cancer has spread. After the lumpectomy, adjuvant treatment is usually administered, mostly radiotherapy. Hormonal therapy may also be administered depending on the type of breast cancer. 


  • Mastectomy: unlike lumpectomy, the surgeon completely removes the breast. Generally, no further treatment would be necessary at this stage, and patients can opt for breast reconstruction (immediate or at a later date). 

Treatment for stage I breast cancer

Stage I is similar to stage 0 in that the tumor is relatively small (less than 2 cm) and has not spread outside the breast but may have spread to nearby lymph nodes. The primary treatment remains surgery, either lumpectomy or mastectomy (with or without reconstruction), as well as possible lymph node removal. Other conventional treatments administered are: 


  • Radiotherapy: as in stage 0, patients who have undergone lumpectomy are more likely to need radiotherapy than those who have undergone mastectomy. In this case, targeted (local) radiotherapy is used on the whole breast to reduce the risk of cancer recurrence. 


  • Hormonal therapy (hormone therapy): indicated for patients whose tumors express hormone receptors (estrogen or progesterone). There are two main types of drugs: 


    • Tamoxifen is a selective estrogen receptor modulator (SERM). This drug blocks estrogen receptors, which prevents breast cancer cells from attaching to them. This prevents the stimulation of cancer growth and division. Tamoxifen is most commonly administered for five years. In some patients, this treatment may be extended for an additional five years since the ATLAS clinical trial showed that taking tamoxifen for ten years reduced the risk of recurrence, reducing mortality by 2.8%. 


    • Aromatase inhibitors: reduce estrogen levels, i.e., stop estrogen production. Inhibitors are taken orally (pill), and the most common are letrozole, anastrozole and exemestane. 


  • Monoclonal antibodies: for those patients with HER2+ breast cancer, trastuzumab (with or without pertuzumab) is usually given for up to 1 year. The physician may recommend neratinib (tyrosine kinase inhibitor) followed by trastuzumab. 


  • Chemotherapy: intravenous adjuvant chemotherapy may be recommended if the tumor has unfavorable or HER2-negative features. The most common early-stage cycles include anthracyclines (doxorubicin or epirubicin) and taxanes (paclitaxel or docetaxel). 

Treatment for stage II breast cancer

Stage II may have larger tumors (2 to 5 cm) or involve a more significant number of lymph nodes. The primary treatment for patients at this stage remains surgery (lumpectomy or mastectomy), accompanied by adjuvant therapy: radiotherapy, chemotherapy, hormone therapy or monoclonal antibodies. 


However, in some cases, systemic therapies (treatment that travels throughout the body rather than being targeted to one area) should be administered before surgery to reduce the tumor size. Neodjuvant therapies that may be employed (in addition to those cited in phase I) are: 


  • Targeted therapy: a combination of tamoxifen or an aromatase inhibitor with abemaciclib (kinase inhibitor). 


  • Immunotherapy: pembrolizumab is recommended for patients with triple-negative breast cancer. 

Treatment for stage III breast cancer

Stage III is considered when the patient presents the following: the tumor is larger than 5 cm, and cancer has spread to many lymph nodes or invades nearby tissues (lymph nodes behind the sternum, thorax or clavicle, among others). There are two ways to treat this stage: 


  • Surgery as the first treatment. In this case, the therapeutic plan is similar to stage II. 


  • Neoadjuvant therapy is the first option. It is more common to approach stage III breast cancer with chemotherapy or targeted therapy to try to shrink the tumor before surgery. If tumor shrinkage is achieved, the patient will undergo a lumpectomy. If the tumor does not shrink, a mastectomy is mandatory. To prevent the disease from returning, radiotherapy and chemotherapy will be used after the operation. In patients with positive hormone receptors, hormone therapy or monoclonal antibodies will be administered. If residual cancer is detected during surgery, the patient will receive ado-trastuzumab emtansine instead of trastuzumab. 

Metastatic breast cancer treatments (stage IV)

The tumor has spread to other organs such as bones, brain, liver or lungs. In other words, it has become metastatic breast cancer. The therapeutic approach at this stage focuses on chronicling the disease without neglecting the patient’s quality of life. Unlike the other stages, the main treatments are systemic: chemotherapy, hormone therapy or immunotherapies. The tumor can present any size, generally large, so local therapies (surgery and radiotherapy) are only carried out in specific cases. The treatment plan will depend on the patient’s general condition and the tumor characteristics, as well as the location of the metastasis. 


  • Hormonal treatment: for patients with metastatic breast cancer with positive hormone receptors, the therapy will depend on whether the woman is: 


    • Premenopausal: it should be considered if the patient previously received tamoxifen or aromatase inhibitors as adjuvant treatment. The primary strategy at this stage is to block the ovaries to prevent estrogen production. One of the ways to achieve this is with ovarian suppression drugs. The most common ovarian suppressants are goserelin (Zoladex) and leuprolide (Tigard, lupron). Another option to stop estrogen production is to perform ovarian ablation, i.e. surgery to remove the ovaries. Once the blockade or suppression is completed, a combination of cyclin inhibitors with letrozole or fulvestrant is indicated. 


    • Postmenopausal: for these as well as male metastatic breast cancer patients, treatment is based on the combination of cyclin inhibitors with letrozole or fulvestrant. 


  • Chemotherapy: this is the primary treatment for negative hormone receptor individuals. There are several chemotherapy drugs available, such as anthracyclines, paclitaxel, docetaxel, vinorelbine, capecitabine, carboplatin, gemcitabine, cisplatin or eribulin. In patients with triple-negative breast cancer, a combination antibody such as sacituzumab govitecan, is available as a second line of treatment. 


  • Targeted therapies: Pertuzumab+trastuzumab or lapatinib+trastuzumab combinations are generally used as the first line. A milestone for patients with HER2+ metastatic breast cancer was achieved in 2022 with the approval of the antibody conjugate trastuzumab deruxtecan. This drug acts as a “Trojan horse” that circumvents tumor cells to enter and destroy them. After excellent results demonstrated in the Destiny-breast03 clinical trial, it has become the preferred regimen as a second and subsequent line of treatment, thanks to its high efficacy and lower toxicity. In addition to trastuzumab deruxtecan, other new molecules act against the HER2 receptor: TDM-1, lapatinib or neratinib.  


  • Monoclonal antibodies: for patients with triple-negative breast cancer whose tumor produces the PD-L1 protein, pembrolizumab or atezolizumab can be used. In HER2+ patients, a combination of bevacizumab and chemotherapy can be administered to prevent the cancer from continuing to obtain nutrients to grow and develop. 


In addition to medical treatment, following a balanced and healthy diet is advisable, together with seeking psychological support to cope with the emotional impact of the disease. Joining a patient advocacy group can provide additional support throughout the cancer process. Patients need to take care of their well-being for a better quality of life

What happens in the case of recurrence?

Recurrence is the reappearance of cancer after a period when it was undetectable. “Relapse” is often used as synonym for recurrence, although slight differences may exist. Relapse occurs when a patient experiences a disease from which they are recovering, whereas recurrence would be the reappearance of the disease after it was believed to be cured. 


Typically, disease recurrences in the same or opposite breast are addressed by surgical procedures, and, in some cases, radiation therapy is considered if it was not previously administered. The choice of additional treatments, such as hormone therapy or chemotherapy, depends on the type of relapse and the previous treatments the patient has received. 


On the other hand, if breast cancer relapse occurs through metastasis, systemic treatments are required, which vary according to the type of breast cancer and may include chemotherapy, hormone therapy, targeted therapies or monoclonal antibodies. 

The positive impact of clinical trials in the treatment of breast cancer and its metastases

Leaders in breast cancer research, such as Dr. Javier Cortés, consider that clinical trials may be the best therapeutic option available on many occasions.  


Participating in a clinical trial means that patients can benefit from access to new therapies, a personalized treatment plan, control of symptoms and side effects that positively impact the quality of life and, for added security, greater follow-up by healthcare personnel. 


In difficult times, searching for research treatments can be incredibly overwhelming, especially when information is so scattered and confusing.  MatchTrial’s mission was to create a clinical trial finder that allows patients to find treatment options in a quick and easy way. With a user-friendly interface, our filtering system allows easy access to all clinical trial information. Our goal is to empower patients to make informed decisions to work together with their oncologist on the best therapeutic approach. Our team of oncology nurses accompanies patients to support them throughout the search process

Research treatments for breast cancer

Why is it necessary to continue researching new breast cancer treatments? 


Every person is different, and so is every cancer. Even every metastasis. Conventional treatments are applied because, in general, they are effective in most patients. However, there are always exceptions, and, in addition, there is the possibility that the cancer may become resistant to standard therapies or recur. Examples of current avenues of research include:


  • New kinase inhibitors. 

  • New selective estrogen receptor degradation

  • Inhibitors specific for the PIK3CA mutation 

  • Bromodomain inhibitors


These new therapies seek to identify and target only malignant cells, which could result in more effective and safer treatments with fewer side effects. 

Clinical trials to improve current breast cancer treatments

The other primary objective of these studies is to reduce the side effects and sequelae of standard breast cancer care. To improve current therapies, different drugs are being tested in combination to increase efficacy, quality of life and survival. Some examples of these combinations under research are: 


  • Abemaciclib (kinase inhibitor) + letrozole or fulvestrant (hormone therapy).

  • Trastuzumab emtansine in combination with atezolizumab 

  • Targeted therapies such as sacituzumab govitecan + pembroluzimab  

  • Allogeneic NK cells + trastuzumab and pertuzumab 

Clinical trials looking for the best treatment plan

Generally, conventional treatments are considered adequate and are administered to most patients. However, humans are unique; this differential trait also applies to tumors and metastases. These singularities that differentiate us drive trials that do not seek to compare drugs but rather to administer the most precise breast cancer treatments adapted to each patient. More personalized therapy means prolonged survival and improved quality of life. An example of an adaptive clinical trial is PHERGain, where doctors modulated the treatment according to each patient’s therapeutic response. 

Get to know the testimonies of patients and survivors with a similar cancer journey

More people like you live with or have overcome breast cancer. Get to know the stories of Silvia, Màrius, Sandra and Tamara


Learn more about clinical trials

Access innovative treatments through our clinical trial finder