| Ch 8 | Page 22 / 25 | |
| Cancer radiotherapy |
Therapeutic associations | |
Radiotherapy is generally associated with surgery and/or chemotherapy and/or hormonotherepy.
Except in palliative situations, radiotherapy may be the exclusive treatment of a few very limited cancers: skin cancer, head and neck cancer, prostate, cervix uteri cancer, anal canal cancer or Hodgkin’s disease.
This is the most frequent association for localised cancers.
As post-operative adjuvant treatment
In order to diminish the risk of local relapse, as soon as surgical healing is obtained, approximately one month after the surgical procedure.
A classical example: breast radiotherapy after lumpectomy (even if adjuvant chemotherapy is planned).
Other examples: cervical radiotherapy after head and neck surgery, brachytherapy after endometrial cancer.
Pre-operative treatment
This treatment is instituted to reduce the risk of per-operatory tumour graft or to reduce the size of tumours in order to render them surgically excisable. Up to the second month after radiotherapy, post-radiotherapy fibrosis is moderate and is not a real obstacle to safe surgery.
A classical example: pre-operative rectal irradiation.
In general, chemotherapy is instituted when tumours have a great dissemination potential, but it can also be proposed in order to reduce the tumour volume before any surgical or radiotherapy procedure when the tumour is known to be chemosensitive.
Irradiation is therefore limited to the initial tumour location.
These associations may also increase the toxic effects of both treatments: haematological toxicity, cardiac toxicity, pulmonary toxicity (cf. the specific toxicities of chemotherapy drugs).
The association of radiotherapy and chemotherapy should not only provide additive effects but also synergistic activity.
New protocols have been set up (still more or less as experimental studies) in order to improve local control and to avoid important surgical mutilation:
- association of chemotherapy and radiotherapy in oesophageal cancer,
- association of radiotherapy, brachytherapy and chemotherapy for advanced cancers of the cervix uteri, in order to avoid mutilating pelvectomy,
- association of radiotherapy and chemotherapy in bladder cancer in order to avoid cystectomy,
- association of radiotherapy and chemotherapy in small laryngeal cancers to preserve the voice.
A noteworthy association of radiotherapy and chemotherapy is prescribed for anal cancer with the FUMIR protocol (5-FU, mytomycin, radiotherapy) or FUPIR (5-FU, cisplatin, radiotherapy) which offer spectacular recovery of this cancer without anal amputation and with conservation of normal anal function. In many cases, these protocols also prove to be efficient for inguinal metastatic nodes of anal cancer.
It is standard to use anti-oestrogens as adjuvant chemotherapy for post-menopausal breast cancer or medical castration for pre-menopausal breast cancer with positive receptors. However, it has not been demonstrated that the use of hormonal treatment potentialises radiotherapy.
Recently, trials in prostate carcinoma have shown that associating medical castration with radiotherapy had a synergistic effect on radiotherapy for locally advanced disease, with increased disease-free survival and, nowadays, increased survival (RTOG trial, Bolla trial). Other trials have since been set up for less advanced cancer disease.
After ablative chemotherapy of acute leukaemia and before allograft, the patient receives total body irradiation in order to avoid graft rejection. The patient receives a dose of 8 Gy (which represents a lethal dose if the patient is not rapidly grafted). This irradiation allows the destruction of the remaining autologous medullar cells which may reject the graft. The tolerance of such irradiation is very poor (as it is for many other aspects of leukaemia treatment).
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