Superficially Invasive Squamous Cell Carcinomas (SISCCA’s) and the upcoming PLATO trial

Superficially Invasive Squamous Cell Carcinoma (SISCCA) is a term that is being increasing used in the literature, and it is defined by the LAST guidelines as  a completely excised Anal SCC (R0) that has an invasive depth less than 3mm from the basement membrane and has a maximum horizontal spread of less than 7mm.  

It is quite interesting that since the LAST guidelines in 2012, more study has gone into whether or not it is possible to spare chemoradiotherapy in this subgroup of patients with small T1 tumours that have already undergone a complete resection.  

Anecdotally, particularly in high HIV positive practices, many Anal SCC’s are identified incidentally after benign colorectal surgery in high risk patients.  There have been documented incidences in conference abstracts where no further treatment was given  after wide local excision only of SISCCA’s with good outcomes.   

Within the Colorectal community, organ sparing approaches such as minimally invasive excisions of rectal lesions are increasing in popularity. As they have larger patient numbers, evidence already exists that T1 rectal tumours can be excised and followed up sparing further operative treatment. The impact on patient quality of life after organ sparing treatment is significant.  

A very interesting paper by Chai et al (2018), is certainly worth a read, it reports the outcomes of treating 2243 T1 Anal SCC’s recorded on the American National Cancer Database.  Its demonstrates that there is no difference in survival outcomes between patients treated with chemoradiotherapy or wide local excision alone. However the use of the American Cancer Database is criticised by several authors in letters to the editor as it is not able to include data on position of tumour, chemoradiotherapy regimes used and recurrence rates. HIV status is also not included. 

In the meantime, The Association of Coloproctology of Great Britain and Ireland Guidelines in 2017, recommended that  SISCCA’s could receive wide local excision alone if technically possible. However, in the absence of peer reviewed research including recurrence and patient outcomes it looked to the ongoing PLATO Trial for further clarification.  

The Personalising Anal Cancer Radiotherapy Dose Trial (PLATO) opened for recruitment in 2017 and is set to release its results in 2028. It is including a study arm comparing the outcomes of T1N0M0 tumours receiving either wide local excision alone or IMRT and Chemotherapy.  

While we wait for the results of the PLATO trial, there remains a real need for further data on Anal SCC’s that includes data outcomes such as HIV status, recurrence data, AIN treatment and previous Genitourinary Dysplastic disease. By including these data outcomes in mASCARA we hope that it will be able to answer the research question that National Cancer Databases are unable to do.  

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