PROPUESTA DE MANEJO DE RESIDUOS SOLIDOS EN LA ZONA RURAL Y URBANA DEL DISTRITO DE KELLUYO – 2013.

6.1 IN T R O D U C T IO N

The epidem iology, natural history and limitations o f current treatment for hepatic métastasés have been discussed in the previous chapter. In a review o f palliative treatment for hepatic tumours, Bengmark (1989) came to the conclusion that there is a need for a simple safe technique whose principle aim would be palliation by controlling local tumour growth. A s survival is dependant on the extent o f hepatic involvem ent, then arresting or reducing tumour volum e may lead to improved patient survival. Alternatively, life quality may be enhanced by delaying the onset o f symptoms arising from compression o f vital stmctures such as the inferior vena cava.

Interstitial therapy, a relatively new concept in oncology goes some way to fulfilling Bengmark's criteria. The term interstitial pertains to the delivery o f a therapeutic modality, for example, heat directly to a selected site where tissue necrosis is required. In the context o f cancer therapy, selective tumour necrosis can be achieved with sparing o f surrounding normal tissue. The focal nature o f tissue damage makes interstitial therapy unsuitable for treating diffuse or multiple liver tumours. Interstitial techniques can be divided according to the type o f agent producing cell death.

1) Heat - for example, laser, radiofrequency and microwaves. 2) Cold - achieved using liquid nitrogen.

3) Chemical means - such as alcohol and phenol. 4) Ionising radiation - using radioactive x-ray implants.

The concept and experimental data on interstitial laser hyperthermia (ILH) have been described in chapter 3. The success and safety o f ILH in treating liver métastasés depends on several interrelated factors.

1) Accurate identification with precise mapping o f tumour extent.

2) Accurate laser fibre placement (preferably percutaneously) within the tumour.

3) Identification o f real time tissue changes and their significance to the extent o f tumour necrosis.

4) Visualisation o f the extent o f tumour necrosis follow ing treatment with subsequent healing.

5) Delineating residual or recurrent viable tumour for further treatment.

The first clinical work using ELH for liver tumours was reported by Hashimoto and his colleagues in 1985. A similar study was performed by Schroder et al (1989) using this technique in 4 patients with hepatic métastasés. In both series, a laparotomy was necessary for laser fibre insertion into the tumours. This makes the technique relatively invasive and excludes those unfit for surgery. In addition, hospitalisation and recovery times are relatively long. Given the palliative nature o f ELH, an operative approach for fibre insertion is undesirable.

Experimental work has confirmed the feasibility o f relatively precise percutaneous fibre placement in animal liver using ultrasound guidance (Bosman et al., 1991, Dachman et al., 1990). The work presented in this chapter is a clinical pilot study using a percutaneous approach with ultrasound guidance for fibre insertion to treat hepatic métastasés. There were two principle objectives. The first was to assess the feasibility o f such an approach for inducing necrosis in liver cancer and secondly to evaluate whether this could be achieved safely. This study had the approval o f the local ethical committee.

By way of contrast, alternative interstitial techniques used in treating liver cancer are reviewed to assess the relative strength and weakness o f each thus providing a basis for what is likely to be the optimum technique. In the absence o f controlled clinical trials, such an assessment must be treated with some caution.

6 2 METHOD

Between November 1988 and August 1991, 21 patients with hepatic métastasés were referred to the National Medical Laser Centre to be considered for ILH. Treatment selection was relatively flexible and included the follow ing criteria. A positive histological diagnosis o f liver cancer was made whenever possible with no remaining evidence o f the primary tumour or extrahepatic spread. No patient was to have more than 4 hepatic deposits with none exceeding a diameter o f 6 cm. All lesions must be accessible to percutaneous

puncture. Patients were to be unsuitable for hepatic resection on grounds o f unfitness, tumour inoperability or to have refused surgery.

Detection o f synchronous hepatic métastasés during resection of the primary, rising tumour markers or surveillance sonography show ing features consistent with hepatic métastasés were the commonest reasons for referral. Eight patient were turned down due to multiple métastasés, extrahepatic spread or excessively large tumours where the probability o f worthwhile tumour regression was considered to be small. Tw elve patients (mean age 64 years, range 53-77 years) with a total o f 33 hepatic métastasés (mean diameter 3.5 cm, range 1.0-11.0 cm) received a total o f 52 laser treatments (range 1-8 per patient) using a percutaneous technique. Patient details are summarised in table 5.01. The primary tumour site was the colon in 6 patients, the rectum in 3 with the oesophagus, stomach and a small bowl carcinoid each accounting for the remaining 3 patients. Five patients had synchronous hepatic métastasés at the time o f resection o f the primary lesion with the remainder developing metachronous métastasés. The mean interval from primary resection to first laser treatment was 30 months (range 5-108 months). Mean follow up time was 20 months (range 4-40 months). Informed consent was obtained from all patients.

Nu m b e r OF Pa t i e n t s A G E ( Ye a r s) P R I M A R Y Ca n c e r Si t e N O . O F HE PA TI C T U M O U R S Me t a s t a s i s Di a m e t e r ( C M ) T O T A L Tr e a t m e n t N u m b e r 1 Male 5 3 - 7 7 75% 33 1.0 - 11.0 52

5 Female Mean = 64 Colorectum Mean = 3.5