I was diagnosed with ESS 14 years ago. It's a cancer with a good survival rate. It's very scary to get that diagnosis though, and it can be difficult to find out about this cancer which is quite rare (though becoming commoner). A few months after diagnosis I found an internet group for ESS sufferers, which I have found a tremendous support. It's good to be able to share some of the anxieties and concerns that other people don't understand. The group I joined is a yahoo group, and I'm still a member, though I don't visit the site so often now. Members share tips about medication and other issues and give general support. They also share information from their doctors and pool knowledge acquired from researching. Some doctors know very little about ESS, while others know a lot. My own gynaecologist had never had another case before mine.
Several doctors and researchers have worked with the yahoogroup, including two American doctors, Dr Ramondetta, a researcher, and Dr Robboy who wrote a text book on ESS. Also a research team from Austria has used volunteers from the group for research. At the start there were fewer than 20 members, but there are now over 350 members worldwide. So you are not alone! If you think you might like to share experiences this way you'll find the group by searching on Google. I am not sure if it's okay to give the address here, but the name is written as one word endometrialstromalsarcoma if you search that and yahoogroups you'll find it. I am sure this will help you with your feeling of isolation. It was such a relief to me.
From the group I'd say Megestrol (Megace) is the basic treatment for ESS. Some ladies in the group have been on it for years, but for some it does have weight gain effects, and some people can't take it, or only for a short time. It's a progesterone and the effects can be like PMT. For me progesterone gives me headaches and moodiness.
In the last few years a more common treatment is an aromatase inhibitor (AI) to drastically reduce levels of oestrogen in the body. The ones used are usually letrozole or anastrozole or exemastane (Brand names Femara, Arimidex and Aromasin). There are quite a few ladies who had secondary nodules that shrank or disappeared with this AI treatment. They are only useful if the tumour is oestrogen-positive.
There are several ladies in the group whose experience was like yours, that the ESS was only found when it recurred somewhere else. The group's longest survivors whose ESS was discovered from secondaries have lived between 20 and 30 years with the disease. Some had tumours as big as 12 cm initially.
What I learned first was that the size of the tumour is significant, that oestrogen should be avoided including oestrogen mimics in the environment and HRT, and that the treatment may depend on whether your tumour had oestrogen and progesterone receptors in the cells. Believe me, you are not alone. There are a few hundred of us. I know the feeling.
I sympathise with your position. My own younger son had just started university when I was diagnosed, and I doubted I'd see him through it. I not only did, I saw him get his masters degree after that, and was able to enjoy his wedding in 2012.
In UK the Marsden hospital in London is the main expert centre, but my own follow up was at the Northern Gynaecological Oncology Centre at Gateshead (Newcastle upon Tyne medics), and has been very good.
I hope this cheers you up, and if you want to join the yahoo group you will find me known as Rosi there. You need to write and a moderator (probably Suzy) introduces you, then share, sound off, ask questions or whatever you want or need!