Long term side effects of Phesgo

Hi BGF,

My name is Gail and I’m one of the cancer information nurses on the Macmillan Support Line.

It sounds as though you’re going through a difficult time.

I'm sorry to hear about the challenges you're experiencing. The symptoms you've described—fatigue, nail problems, joint pain, neuropathy in fingers and toes, and muscle cramps—can be associated with long-term use of trastuzumab and pertuzumab, including their combination in Phesgo.

Although most symptoms can get better if a treatment is changed, it’s important we monitor Peripheral neuropathy more closely to prevent irreversible damage. Your consultant will want to intervene and consider other options before causing too much damage. Most symptoms with the exception of peripheral neuropathy can get better after a break or change of treatment, although this can take time.

Although an appropriate treatment can effectively impact the cancer cells, it’s important to ensure we can do that safely whilst minimising symptoms that are directly impacting your quality of life. The clinicians continuously assess if the benefits outweigh the risks. Sharing how your symptoms are affecting you physically and emotionally, can offer your team further insight. It can open a discussion between you and your Oncologist, allowing you to be part of that decision making, offering further clarity about your options to alleviate or minimise these symptoms.

They may discuss a dose reduction, which can allow you to continue an effective cancer treatment, whilst alleviating or minimising side effects.

Generally, each person is initially given 100% dose, and this is calculated using your height, weight and surface area. Sometimes a decrease of 20-25% can also be considered, as this can also minimise side effects. Sometimes a break from treatment can also be considered.

You may already be on medication to help with pain caused by peripheral neuropathy, muscle cramps etc, but it’s important to consider other alternatives. We don’t want you ‘struggling’ when small interventions can have such a positive impact.

Muscle cramps can be further enhanced if your Magnesium level is low. Your magnesium level is not always checked routinely when carrying out blood tests prior to treatment but can easily be added to determine if supplements could benefit you.

It can be difficult to ascertain if fatigue and joint pain, are related to menopausal changes or your treatment. Distinguishing between treatment-related side effects and menopausal symptoms can be challenging, however, it’s still important we try to address these. If you decide to try a treatment to alleviate menopausal symptoms, always speak with your cancer treatment team first to ensure there are no contraindications with your cancer treatments

The overall aim is for you to continue an effective cancer treatment whilst ensuring you can have a quality of life. Sometimes, it can take time to find the best medicines to counteract your side effects. It’s important to keep your cancer team updated as then other interventions can be considered until we find the best balance for you.

I can hear you’re struggling, but please don’t feel you need to cope with this alone. If you feel it might help, you can talk directly to our nurses on the support line and we’d be more than happy to answer any questions and offer clinical guidance as well as emotional support.

I hope this information is helpful. If you have any further questions, please get in touch by email, webchat or phone. The Macmillan Support Line offers practical, clinical, financial, and emotional support. You can call us free from landlines and from most mobile phone networks* on 0808 808 00 00, 7 days a week, 8am – 8pm. You can also visit our Online Community, where you can talk to others who have been affected by cancer. 

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Take care